Given everything that goes into making a video game, it's amazing cameo appearances happen at all. For the most part, they're side content, separate from the main game. They can require input from publishers, developers, lawyers and sometimes actors. That's a lot of effort to put into something that's ancillary to the experience. So, why do they do it?

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Well, for the same reason they make games in the first place: It's really cool. There's an excitement that comes from seeing a familiar character in a new place. Whether it's a complete surprise or a reward you actively seek out, a well-placed cameo can have a noticeable effect on your enjoyment of a game. In that spirit, we've collected 19 of the best cameos video games have to offer.

19 SPAWN & LINK (SOUL CALIBUR 2)

The original "Soul Calibur" was easily one of the best fighting games on the Dreamcast. By the time the sequel came out, the Dreamcast was dead and "Soul Calibur II" went multi-platform. Best of all, each version of "Soul Calibur II" got its own unique cameo. Playstation 2 owners got Heihachi from Tekken, but the most exciting cameo appearances were reserved for the other consoles.

Xbox owners got Spawn (created by Todd McFarlane), whose cape takes the form of a double-edged axe called Agony, giving him a medium-to-short range fighting style. Although, his Necroplasm fireball made him a dangerous opponent at any distance. Gamecube owners, on the other hand, got arguably the most exciting cameo: Link, from "The Legend of Zelda." He primarily uses his Master Sword, but makes use of a wide array of familiar weapons, including the boomerang, bow and arrow, and bombs. As surprising as it was to see Link in a non-Nintendo game, his versatile fighting style fit perfectly into the world of "Soul Calibur."

18 DAREDEVIL (SPIDER-MAN, PSX)

"Spider-Man," developed by Neversoft and published by Activision, set a high bar for superhero games back in 2000. In an era where licensed games were usually low-quality rush jobs, Neversoft put a lot of care into making a Spider-Man video game that was fun to play and faithful to the comics. The story involves Doctor Octopus and a Spider-Man imposter enveloping the city in fog. Over the course of the game, you fight a variety of Spider-Man villains including Rhino, The Scorpion and Mysterio.

Daredevil also stops by to lend a helping hand. Since there's a Spider-Man imposter out there, the cops naturally think the real webslinger is guilty. Daredevil hears him out, listening to his heartbeat, and determines he's telling the truth. He spreads the word of Spider-Man's innocence and gets the cops off his back. (Good thing, too, because the preceding chase sequence was annoyingly difficult.) Daredevil makes another appearance during the epilogue, along with Captain America and The Punisher, joining Spidey for a friendly poker game.

17 FREDDY KRUEGER (MORTAL KOMBAT)

Technically the ninth game in the series, 2011's "Mortal Kombat" starts right after the events of "Mortal Kombat: Armageddon." Raiden is about to be killed by Shao Khan, but he's able to send a message to his past self. The story then rewinds back to the beginning of the original "Mortal Kombat," and the story begins anew.

"Mortal Kombat" (2011) was a return to form in every possible way. It was a fast-paced 2D fighter with gory fatalities and all your favorite characters. You might expect, then, that any cameos might feel out of place. Thankfully, that would be wrong. NetherRealm brought in Freddy Krueger as DLC. With the extreme violence of the fatalities, Freddy was a natural fit. His abilities allowed him to destroy enemies in all sorts of nightmarishly violent ways, including burning them alive, just like he was. Hilariously, his story in the game ends with him being banished to the Dream Realm, making "Mortal Kombat" a prequel to 1984's "A Nightmare on Elm Street."

16 PREDATOR (MORTAL KOMBAT X)

Coming off the success of the ninth "Mortal Kombat" game, developer NetherRealm doubled down on everything that made their previous entry a success. The feel of the fighting engine was largely retained, but some added complexity made the fights more fun and varied. Since the addition of Freddy Krueger was so successful in the last game, NeatherRealm brought in even more horror movie characters for this one, including Jason Voorhees, the Alien, and best of all, Predator.

Predator has all the abilities you'd want, the most useful of which being Stealth. As the name implies, Stealth makes you invisible. Now, this being a 2D fighting engine, there are only so many places you can be, but the uncertainty means you might be able to get a surprise hit in. Even better, it lowers the amount of chip damage you take while blocking. Predator's wide assortment of weapons also allows for some brutally gory fatalities. The one involving his wrist-blades and smart disc is particularly disturbing.

15 SPIDER-MAN (THE REVENGE OF SHINOBI)

The best Genesis game to feature Spider-Man and Batman didn't even let you play as them. Instead, you fought them. Well... sort of. In the initial release, you fought a shapeshifter who turns into an off-brand Batman and Spider-Man. Enemies resembling Rambo, The Terminator and Godzilla were also present. In subsequent releases of the cartridge, Batman was changed into a devilish figure, and everyone but Spider-Man had their sprites edited to be less copyright-infringing.

Spider-Man not only stayed in the game, but was eventually made official. Sega licensed the character from Marvel to make "The Amazing Spider-Man vs. The Kingpin." That deal allowed them to dispense with the shapeshifter altogether and just have you fight Spider-Man in the later printings of the cartridge. He crawls around on the ceiling, shooting webs at you, and occasionally drops down on a web to hit you. Sadly, the license was only for a limited time and Spider-Man is not present in modern ports of the game.

14 NOLAN NORTH (DEADPOOL)

Before Ryan Reynolds and director Tim Miller gave us the quintessential big screen version of the Merc with a Mouth, this 2013 game was the closest we had to a faithful "Deadpool" adaptation. The game itself was a fairly standard action beat-em-up. The gameplay wasn't all that great, but the writing, the humor, the complete disregard for the fourth wall, was perfect.

Probably the funniest fourth-wall-breaking moment comes early on in the game. Deadpool, voiced by Nolan North, sets off explosives at a game studio, and forces them to make an awesome video game starring him. He receives a script, but quickly gets bored, scribbles on it in crayon, and decides to improvise. Before jumping into action, he makes a phone call. A modern video game needs voice actors, and who better to voice our hero than the most prolific actor in all of gaming, Nolan North? Yes, Nolan North (playing Deadpool) calls Nolan North (playing himself) asking him to be in the game they're both already in. Doesn't get more Deadpool than that.

13 SPIDER-MAN (TONY HAWK'S PRO SKATER 2)

The Tony Hawk series is famous for its fun, fast skateboarding action and its fantastic punk and hip hop-filled soundtrack. These games introduced an entire generation of gamers to bands like The Dead Kennedys, Bad Religion and Naughty by Nature. Who doesn't remember restarting a level over and over again so they could skate to their favorite song? The second game in the series added larger levels, a more diverse soundtrack, a level editor, and new secret characters.

Since Neversoft also developed the Spider-Man video game (using the "Tony Hawk 2" engine), it was only natural that the webslinger would test his skills at the skate park. Players unlocked your friendly neighborhood Spider-Man by completing all the objectives in career mode with a created skater. For that work, they were rewarded with one of the best characters in the game. If you were looking to pull off a million-point combo, he could get the job done. And he used his webbing to pull off impossible tricks, making him one of the most fun characters to play as well.

12 HIDEO KOJIMA (METAL GEAR SOLID V: GROUND ZEROES)

Considering how much Hideo Kojima likes to insert in-jokes into his games, this might be the least surprising cameo on this list. From the "Metal Gear" robot in "Snatcher" to the "Metal Gear Solid: Peace Walker" hidden "Kojima is God" codec conversation, the legendary game designer has always enjoyed referencing himself and his resume in his work. Kojima took things a step further in "Metal Gear Solid V: Ground Zeroes" by literally inserting a performance capture of himself into the game.

In the game, Hideo requests extraction from a U.S. prison camp in Cuba, but his cover is compromised. Big Boss must undertake a difficult mission to rescue and recruit him. The mission involves providing cover fire from a helicopter, rescuing Kojima alive from a base where everyone is trying to kill you and escaping while firing rockets at your pursuers. Being the creator of the game, Kojima expects perfection. Normally, upon completion, he'll ask what took you so long. It's only if you get an S-rank that he'll say, "Snake, that was perfect."

11 SCORPION (INJUSTICE: GODS AMONG US)

After the success of "Mortal Kombat," NetherRealm used the same engine to make a fighting game the entire family could enjoy. Like "Mortal Kombat," "Injustice: Gods Among Us" was a fun, complex but easy-to-pick-up fighter with outlandish special moves. Only, instead of Mortal Kombat characters, it starred DC superheroes; and instead of gory fatalities, "Injustice" had special moves that showcased each hero's powers. (One highlight was The Flash running around the Earth to punch his opponent extra hard.)

Of course, being on the same engine as "Mortal Kombat," it only made sense that a fan favorite from that series would come to visit. His move set was largely unchanged, only now they don't cause blood to spurt from his opponents' bodies. He retained his Bloody Spear attack, "get over here," but it was significantly less bloody. Scorpion's special move was also surprisingly brutal for a T-rated game. He would kick his opponent into the Nether Realm, drag them around with his spears and slam them against the walls and ground. That's a deadly attack, even against Superman.

10 MICHAEL JACKSON (SPACE CHANNEL 5)

The Dreamcast was a weird, interesting console with a lot of weird, interesting games. Sadly, the system was discontinued only a couple of years into its life, but its eclectic collection of oddities is still beloved by gamers today. One such odd game was "Space Channel 5," a music game starring Ulala, a space reporter who rescued people from aliens using the power of dance. That's just the kind of system the Dreamcast was.

Being such a strange and wonderful game, it's only natural that it features a strange and wonderful cameo. One of Ulala's coworkers at Space Channel 5 was Space Michael, a character modeled after (who else?) Michael Jackson. The late King of Pop even voiced the character. Though he made only a brief appearance in the first game, Space Michael's role was expanded in "Space Channel 5: Part Two." After Ulala rescues him in that game, he dance-fights a singing robot and joins Ulala in battle. The Dreamcast was truly something special.

9 BILL & HILLARY CLINTON (NBA JAM, READY 2 RUMBLE 2)

Who says games can't be political? "NBA Jam" was everyone's favorite arcade basketball game. With frenzied back-and-forth action and physics-defying dunks, "NBA Jam" burned the phrase "he's on fire" into every young gamer's brain. Given where real life basketball was at the time, players most probably chose to play as the Chicago Bulls, and dominate the court as Horace Grant and Scottie Pippen. (Midway wasn't able to secure Michael Jordan's likeness rights.)

When it got ported to home consoles, all sorts of secret characters made cameo appearances. Most notably, then-U.S. President Bill Clinton and First Lady Hillary Clinton could take the court and go up against some of the greatest basketball players of all time. That wouldn't be the Clintons' only foray into video game sports, though. The political power couple later made an appearance on the Sega Dreamcast in "Ready 2 Rumble Boxing: Round 2." That's a cameo anyone could enjoy, no matter what side of the aisle they're on.

8 SOLID SNAKE (SUPER SMASH BROS. BRAWL)

The Super Smash Bros. series is built on cameos. In fact, when a new game comes out, the most exciting part of the pre-release hype is speculating who will make a surprise cameo appearance. At this point, we know the main roster of Nintendo characters will be in each game. Mario, Luigi, Link, Fox, Pikachu, Samus Aran and pretty much every character ever featured in a Nintendo-developed game is guaranteed to appear on the ever-expanding roster. It's the guest characters, the non-Nintendo characters, that surprise us on each console generation.

Probably the most surprising and exciting guest appearance was Solid Snake showing up in "Super Smash Bros. Brawl" for the Wii. As the star of an M-rated game, his presence was definitely unexpected in the usually kid-friendly fighter. But there was a Gamecube-exclusive remake of the original "Metal Gear Solid," so that was enough for Snake to join the brawl. It was a little strange to see someone firing guns at Mario and the gang, but there was nothing more satisfying than hitting your final smash and watching opponents run around the stage in terror as you aim your grenade launcher.

7 CREEPERS (BORDERLANDS 2)

"Borderlands 2" is all about variety. With six playable characters and somewhere around 17.75 million weapons, this game is all about showing you something new and unexpected at every opportunity. The game also doesn't take its own lore seriously at all, making it easy for characters from other games to show up for cameo appearances.

Hidden in a secret cave in the Caustic Caverns area is one recognizable foe. After crossing a mine cart bridge, you'll come to an area with strange square-shaped boulders and breakable blocks of dirt. Keep tunneling through, and you'll run into a mass of creepers from "Minecraft." The creepers, as their name suggests, creep towards you and explode when they get close. Fight through all of them, and you'll meet the Badass Creeper, a much larger variant that causes a bigger, deadlier explosion. Defeat the Badass Creeper, and you'll find either a head or body skin that turns you into a "Minecraft" version of your character.

6 MICHAEL MEYERS (CALL OF DUTY: GHOSTS)

Unlike many of the other games on this list, "Call of Duty" tends to take it self extremely seriously. You wouldn't normally expect any kind of cameo appearance in a military action shooter like 2013's "Call of Duty: Ghosts." That's why it was such a welcome surprise when Michael Myers from "Halloween" showed up in the "Onslaught" DLC pack.

Michael Myers is a Field Order Reward in the Fog multiplayer map. Once a player obtains the reward, their character becomes the Swamp Slasher. Myers is a formidable presence on the map, with an axe that allows for a fast, deadly melee attack. He's also terrifyingly fast and regenerates a small amount of health for every person he kills. If the prospect of that emotionless mask leering over you isn't horrific enough, the nursery rhyme from the "Halloween" movies plays when someone finally takes him out. Who knew "Call of Duty" could be so scary?

5 GARY COLEMAN (POSTAL 2)

"Postal 2" was highly controversial by design when it came out in 2003. Filled with gratuitous violence and racial stereotypes, it was banned in multiple countries shortly after its release. While the gameplay wasn't anything special, its living, open world was an impressive technical achievement at the time. Of course, what most people remember it for is a cameo appearance that happens in the early stages of the game.

Postal Dude has to travel to the mall to get Gary Coleman's autograph. Once at the mall, everything about the level is designed to test the player's patience. The line is insufferably long and it's so easy to just start shooting up the place. If you do wait in the line, Coleman will simply sign Postal Dude's book. No matter what, the police show up to arrest Coleman and a shootout ensues. Whether Postal Dude contributes or not, the police seemingly kill the actor. Later, when you break out of prison, you find that Coleman is also in jail, and set him free.

4 FRED DURST (FIGHT CLUB)

This one came out of nowhere. First of all, the existence of a video game based on "Fight Club" is weird. The fact that it features a cameo by Limp Bizkit frontman Fred Durst makes it sound like some sort of fever dream. The game itself was not all that fun to play, with its simplistic fight system and stilted animations. Normally, you play as a character called only Hero. He joins Fight Club after a bad breakup and eventually becomes Tyler Durden's second-in-command.

Once you complete the story mode, you can play it again as Fred Durst. He doesn't bring much to the game other than some circa-2004 rap rock poses before fights. Why is Fred Durst in there? No one knows. His first appearance in a video game was "WWF Smackdown: Just Bring it!" That at least made sense because of Durst's affiliation with the WWF (now WWE) at the time. As Durst has nothing to do with "Fight Club," it's anybody's guess why he's in the game.

3 MIGHTY BOMB JACK (TECMO SUPER BOWL)

There's some debate over whether the original "Tecmo Bowl" or its sequel, "Tecmo Super Bowl" is the better NES football game. The latter has the edge of every NFL team and player from that era (minus a couple quarterbacks who withheld their likeness rights). It also has another important element that is missing from "Tecmo Bowl" -- a cameo appearance from Mighty Bomb Jack.

Mighty Bomb Jack was a simple platformer Tecmo made for the NES with a quirky sense of humor. When Tecmo made the sequel to its first hit NFL game, they realized you can't have a super bowl without an awesome halftime show. It's what half the real-life audience watches the game for in the first place. So, what better guest star to perform the halftime show than Tecmo's most recognizable character, Jack? At halftime, three Jacks come onto the field and perform a dance involving cute aerial routines. It culminates with the three little Jacks combining to form on big Jack, who flies around the arena. It's honestly a better halftime show than some real Super Bowls have had.

2 MAX (JEDI KNIGHT: DARK FORCES 2)

If you were a PC gamer and a "Star Wars" fan in the mid-1990s, chances are the Dark Forces/Jedi Knight series ranked among your favorite games. In addition to making "Star Wars" games, developer LucasArts was also famous for its hilarious point-and-click adventures. Given the dev team's well-known sense of humor, it's only natural that their games were filled with in-jokes and cameos.

Max, the homicidal bunny from "Sam and Max Hit the Road," makes an especially memorable appearance in "Star Wars Jedi Knight: Dark Forces 2." In "Level Five: Baron's Hed – The Fallen City," you can sneak into a building after a woman opens the door to leave. Inside, you find Max holding a pistol. Interact with the bunny, and he'll fight alongside you for the rest of the level. If you interact with him again, you can even see things from Max's perspective. Just don't fire your gun at him. He won't take kindly to that and will promptly return the favor.

1 JOE KELLY (XCOM: ENEMY UNKNOWN)

Developer Firaxis breathed new life into the X-COM series of classic turn-based strategy games when they released "XCOM: Enemy Unknown" in 2012. The game had players fighting off an alien invasion with a squad of randomly generated soldiers. If one of them died on a mission, they were gone forever. Depending on the difficulty you chose, a random dice roll could permanently take out your best character.

If you wanted a break from all that tension, you could recruit "Heroes." These super soldiers basically acted as cheat codes for "XCOM." They had high stats and special abilities that made missions much easier to complete. One such hero was comics writer Joe Kelly of "Deadpool," "Uncanny X-Men," and "JLA" fame. In the game, Kelly has 100 Aim and Will stats. More importantly, he has a 100 percent chance to land a critical hit. With him on your team, you can pretty much walk through any mission the game throws at you. Who know comic book writers would be so valuable during an alien attack?

What was your favorite cameo in video games? Let us know in the comments!