The only thing harder than making a good first film is a great follow-up -- especially in the ever-growing crowd of comic book movies. For every "X2" or "The Dark Knight" gracing the multiplex, there's an underwhelming "Amazing Spider-Man 2" or "Fantastic Four: Rise of the Silver Surfer" on the books.

Fox's "X-Men: Days of Future Past" is the latest sequel -- or, to quote director Bryan Singer, "inbetweenquel" -- gunning for a shot at great sequel status. And while the film is in the unique spot of being both the latest chapter of the ongoing X-Film series and a direct continuation of the events in "First Class," "DOFP" spends significantly more time with Young Xavier, Magneto and Mystique than it does the original crew (other than Wolverine), furthering the "First Class" story in a way that feels more like a "Part 2" than a "Part, well, whatever number it would be" in the original films. Effectively, Matthew Vaughn's retro-mutant film was nearly as much a reboot as Marc Webb's "Amazing" was to Sam Raimi's "Spider-Man."

REVIEW: "X-Men: Days of Future Past" Gives "Avengers" a Run for Its Money

With that in mind, CBR takes a look at the other direct sequels featuring the heroes of the Marvel Universe -- and there are a lot! Where do the latest X-Men movie, "Captain America: The Winter Soldier" and "Ghost Rider: Spirit of Vengeance" place on our list of Marvel's Best Part 2's? Read on and find out!

Fantastic Four: Rise of the Silver Surfer

The only thing this movie gets right -- which the first film got so, so wrong -- is showcasing the titular team working together to save the world, instead of always in-fighting. "FF2" is guilty of many things, but high on its list of offenses is turning the iconic Galactus into a big cloud thing. That's grounds for a life sentence in movie jail.

Ghost Rider: Spirit of Vengeance

"Spirit of Vengeance" is not the worst movie ever made. But it's definitely its cousin.

Whereas the first "Ghost Rider" film took itself way too seriously, "Vengeance" embraces its badness while not quite being in on the joke. The end result is an inept mix of shaky-cam set pieces and incredulous plot; a very guilty pleasure. Minus the pleasure part.

The Amazing Spider-Man 2

From a ten-minute prologue that insists on building the back story of Peter Parker's parents -- characters we didn't care about the first time around -- to having Electro's origins mirror those of Edward Nigma in "Batman Forever," Marc Webb's second Spider-Man film continues to do everything different from Raimi's series, while improving on nothing.

Well, almost nothing -- the chemistry between Peter (Andrew Garfield) and Gwen Stacy (Emma Stone) resonates more than that of Spidey and Mary Jane, played by Tobey Maguire and Kirsten Dunst, respectively. But two appealing leads aren't enough to make up for a script that plays out like a live-action mad-lib of studio notes, resulting in a film more concerned with setting up future films than making this one the best it can be. Spider-Man is an A-plus hero; his films should compel audiences to see them again instead of making them wonder, "Why did we bother at all?"

Thor: The Dark World

Thor's reunion tour with Midgard comes with a lot of moving parts, but few of them connect on any real emotional level, and those that do are drowned out by the thud of too much world-building exposition.

Director Alan Taylor finds interesting ways to make Thor's universe more cinematicly intriguing than Kenneth Branagh did in the first film; unfortunately, "Dark World's" story can't keep up with the film's impressive production values. The movie fails to find anything substantial for its villain to do, outside of saying vaguely threatening things in between CG battles. And if Chris Hemsworth's Thor fairs slightly better, it's due to two things: His scenes with Tom Hiddleston's Loki and their undeniably addictive screen presence. A genuinely inventive set piece in the third act almost makes up for the disappointing action of the first two, but it's not enough to justify many repeat viewings.

Iron Man 2

Marvel Studios' first misfire of the Phase One film series is for Iron Man what "Quantum of Solace" is for Bond: A messy follow-up to a surprisingly successful first film. It's a collection of good intentions that struggle to find the bullseye for two hours, grinding to a stop simply because it's reached the end credits.

This bloated sequel goes off the rails quickly, somewhere around the time Mickey Rourke's Whiplash bonds with his exotic bird. It soon takes on the characteristics of a train wreck when Iron Man and War Machine defeat the villain by, essentially, high-fiving him with their laser hands.

The Incredible Hulk

Marvel's pseudo-reboot of Ang Lee's "Hulk" plays enough like a loose sequel to that much-maligned film to warrant placement here. Of Marvel's Phase One films, it's the least-showy and (arguably) the most grounded -- until that Abomination vs. Hulk battle royal. But "Incredible's" take on Bruce Banner by way of "The Fugitive" gives the movie some much-welcomed dramatic weight, more so than most of Marvel's early blockbusters.

Blade II

Guillermo Del Toro's "Blade II" owes much of its sensibilities to James Cameron's "Aliens," with a story centered on the titular hero teaming up with a badass special forces team of vampires to take down a new threat that feeds on both vamp and humankind. The CG is late-90s videogame bad in sections, and the infusion of wrestling moves into final fights is campy fan-service, but "Blade II" succeeds mostly for the way it embraces its comic book roots. In doing so, the film delivers the R-rated goods in the way "Spirit of Vengeance" failed to do.

The Wolverine

James Mangold's "The Wolverine" is the X-Man's best solo movie, and it could have been one of the best comic book films ever, if not for a truly messy, disappointing third act. (The best way to extract Logan's DNA is to drill into his bone claws? Because science? Really?!)

As problematic as the last third of the film is, the first two-thirds of this ronin samurai-esque thriller succeed in all areas where "X-Men: Origins" failed: Putting Wolverine front-and-center in his own movie, free of distracting mutant cameos, to tell a story of how an immortal killer comes to terms with death -- especially his own mortality. Beautifully shot and tightly paced, with an occasionally haunting performance by Hugh Jackman, "The Wolverine" unfortunately falters under the weight of its heavy emotional themes when it's more comic book-y elements fail to support it.

Captain America: The Winter Soldier

"Winter Soldier" effortlessly finds ways to make their superheroes relatable in between ILM-powered action scenes, culminating in an exciting spy thriller that just happens to star Captain America and Nick Fury.

The set pieces are crazy inventive and the performances, particularly Chris Evans' Cap, are damn good. It's the best second installment Marvel Studios proper has produced so far. And the only reason why we didn't bump it higher on the list is that, after one viewing, you've kind of mastered all the film is trying to say. As fun as a second and third watching of "Soldier" is, its novelty wears off faster than that of our Top 3 films.

X-Men: Days of Future Past

Bryan Singer's third X-Men film is an intimately-scaled epic that is hard not to love -- click here for our review to see why.

In short, Singer takes all the things we love about this series, honors them, then enhances them with a time-travel story that finds Wolverine working across two time periods to save the X-Men from extinction. The enhancement comes thanks in large part to the filmmaker's gift to take these characters seriously without feeling too precious about it, doubling-down on character development in a way that makes the film's more comic book-y elements easier to swallow. While most blockbusters default to citywide destruction for final-act showdowns, "Future Past" refreshingly takes a different tact, opting instead to mine its characters for maximum impact rather than allowing the CG take over. It's not the best movie ever made, but it's one of the best times at the movies you'll have all year.

Spider-Man 2

The impressive webslinging action and CG spectacle aside, Sam Raimi's first -- and best -- Spidey sequel is more interested in the emotional toll being a hero takes on Peter Parker than it is in the physical one.

The film's final scene, a haunting image of a conflicted Mary Jane watching her boyfriend's alternate identity swing into yet another crisis, delivers more impact in a single shot than most films muster during their entire running time. While Christopher Nolan's Batman trilogy surely raised the bar that all modern comic book films now must meet, Raimi raised it first with "Spider-Man 2."

X2

At the time of its release, the sequel to Fox's 2000 hit was praised as "The Wrath of Khan" of comic book movies -- and for good reason.

Singer's second trip to the X Mansion grounds the action in thematic territory similar to that of "Trek II," as the X-Men are forced to team up with Magneto and his Brotherhood of Mutants to take down a very human threat to mutantkind.

From the riveting opening set piece, with Nightcrawler BAMF-ing around the White House to assassinate the President, to an inventive sequence pitting the X-Jet vs. military fighters, "X2" surpasses "X1" in every way. The emotional stakes are higher, the narrative never runs out of ways to challenge our heroes and the performances -- particularly Hugh Jackman, Patrick Stewart and Ian McKellan -- are some of the genre's best. And no, that's not dust in our eyes when a certain X-Man pulls a Spock to save her friends. Those are pure, unabashed tears.