Over the course of seven seasons and 144 episodes, "Buffy the Vampire Slayer" introduced its audience to dozens of villains. Week after week, Buffy Summers and her ragtag team fought back the forces of darkness and prevented the Earth from being swallowed up by Sunnydale, California's Hellmouth. The show even popularized the phrase "Big Bad," which was coined to describe the villains at the heart of each season's yearlong story arc.

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Not all villains were created equal, though. Many of those bad guys were defeated during their lone primetime outing, usually turned to dust by one of Buffy's well-placed stakes. This list isn't for the likes of Ted or the Gorch Brothers, though; this list is for the biggest Buffy bads of all time.

15 ETHAN RAYNE

If there's mass confusion in Sunnydale, it's probably because chaos wizard Ethan Rayne has rolled into town. This British bad guy caused trouble in four "Buffy" episodes, and he tended to not narrow his focus on just the Slayer's Scooby Gang. In "Halloween," Rayne's enchanted costumes transformed the wearer into whatever they were dressed as. Ethan's spell in "Band Candy" reverted every adult in Sunnydale back to their hedonistic, hippy teenage selves.

Rayne also had close ties to Buffy's watcher, Giles, as they got into demon-conjuring trouble back in Britain during their youth. Rayne's other two appearances saw him target Giles, specifically in season four's "A New Man." Rayne turned Giles into a lumbering Fyarl Demon. Ethan was later forced into reversing the spell. His time on "Buffy" came to an end right then, as the government-funded demon-hunting program called the Initiative tracked him down and captured him. Ethan's unique brand of madness stopped right then.

14 CALEB

Even though Caleb only appeared in the very final five episodes of "Buffy," he still left his mark. Played by frequent Joss Whedon collaborator Nathan Fillion, fresh off of "Firefly," this deranged preacher also left his mark on Xander by gouging his eye out. Caleb's super strength stemmed from the First Evil, who imbued him with abilities far beyond anything Buffy and her team had encountered before. Caleb was able to go toe to toe with Buffy and dozens of other potential Slayers, swatting them all away like flies.

The Bible verse-spouting Caleb met his match, though, in the final episode of the series. Using a powerful and ancient scythe, a weapon specifically crafted for use by the Slayer, Buffy managed to cut past the First Evil's defenses and directly into Caleb. After a slice to the stomach wasn't enough to kill him, Buffy went right down the middle and split Caleb in half, vertically, from the groin up.

13 SWEET

Sweet may have only appeared once in the entire "Buffy" TV series, but his lone skirmish with the Slayer's team was one of the most memorable. Sweet used his unique demonic powers to turn the town of Sunnydale into the setting of a rollicking musical, complete with totally choreographed dance numbers and a nonstop barrage of musical interludes. Everyone in Sunnydale found themselves the star of their own classic Hollywood musical, including Buffy and her pals.

This wasn't all fun, though, as it was eventually revealed that Sweet's song and dance numbers would ultimately lead to people's insides catching fire. Before combusting, the performers revealed their deepest, darkest secrets through song -- and Buffy's crew had plenty of secrets to share. While Sweet didn't get the child bride that he came for (it turned out Xander accidentally summoned him, not Buffy's sister Dawn), he did get the last laugh; he teleported out of Sunnydale, leaving the Scooby Gang to deal with all their exposed truths.

12 ADAM

"Buffy's" fourth season saw the team pull up stakes from Sunnydale High (which was easy, since it was thoroughly blow up at graduation) and move on to college. The change in setting coupled with the unique threat of the government-funded Initiative resulted in an odd season. The Big Bad of season four, the Frankenstein's monster-esque Adam, isn't one that fans look back on with fondness or fear, really. The real Big Bad of season four was the Scoobies themselves, as they drifted apart from each other over the course of the season, only to reunite in their battle against Adam.

Still, Adam was menacing, and his cold and logical brain made him unsympathetic to even his closest allies. This guy even murdered his own creator! His robotic enhancements and demonic spare parts also made him capable of defeating Buffy time and time again. Buffy only defeated Adam by magically imbuing herself with the added strength of Willow, Xander and Giles. Adam may not be a favorite foe, but he sure was a formidable one.

11 THE TRIO

Similar to Adam the surface-level Big Bads of season six were also red herrings used to distract from the real, intangible villain. The geeks of the Trio (Warren Mears, Jonathan Levinson, and Andrew Wells) all had previous ties to Buffy and their own reasons for wanting to level-up by becoming her whatever-the-plural-of-nemesis-is. Buffy saved Jonathan's life on countless occasions back in high school, but his attempts to boost his own self-esteem went nowhere. Buffy busted up Warren's gig of creating robotic girlfriend replicas, which made him hate the Slayer. Andrew's older brother Tucker crossed paths with Buffy at Sunnydale High, while Andrew was, mostly, just along for the ride.

While the real Big Bad of season six was more or less adulthood, the Trio still made their presence felt. They trapped Buffy in a number of dangerous scenarios involving time loops, invisi-rays and demons. Things took a dark turn, though, when Warren said "screw it" and resorted to using a gun. One of his stray bullets ended up hitting and killing Willow's girlfriend, Tara.

10 DRUSILLA

A show called "Buffy the Vampire Slayer" has gotta have some evil vampires in it, obviously, and Drusilla definitely fits that description. Along with some other vamps on this list, Drusilla acted as one of the major threats during season two. Her twisted Bonnie and Clyde-style relationship with Spike proved that vampires don't have to have souls to express what they consider love. The two of them caused a lot of trouble in Sunnydale, summoning demons capable of genocide and just generally causing mayhem. Drusilla even bagged herself a Slayer in the season two finale when she used her snakelike hypnosis ability to distract Kendra and then slice the hypnotized Slayer's neck clean open.

From "Buffy," Drusilla went on to the spinoff series "Angel" and wreaked even more havoc over on that show. She would return to "Buffy" on a handful of occasions, mostly to bemoan the increasingly pathetic (in her opinion) state of her former lover Spike as he got bogged down with noble intentions and, eventually, a soul.

9 THE GENTLEMEN

Like Sweet, the Gentlemen were a one-and-done monster of the week that had a lasting impact on fandom. These fairy tale monsters floated into Sunnydale during the season four episode "Hush," the series' silent episode that went on to become a fan favorite. The Gentlemen stole the voices of the entire town, in order to better sneak into a select group of homes and steal their owners' hearts. After all, without a voice, victims can't scream.

Of course, the Gentlemen hadn't encountered a town with a Slayer in residence before, and Buffy and her team quickly set about finding a way to stop the monsters' well-dressed reign of terror. Buffy broke into their temporary nesting ground and, with the help of her soon-to-be-boyfriend Riley, smashed the mystical box containing the voices of everyone in Sunnydale. Buffy hit upon the Gentlemen's real weakness: the human voice. Buffy's human shriek caused all of their heads to explode, thus robbing us of further Gentlemen appearances.

8 THE FIRST

The final season of "Buffy" came full circle by taking the Big Bad trend all the way back to the beginning -- the very beginning. In the last season, Buffy fought the concept of evil itself -- a being so old it predated both man and demon. The First made a one-off appearance in season three, tormenting Angel with the images of everyone he had ever murdered. Buffy intervened in the First's attempt to drive Angel to suicide, but that wouldn't be the last time the First would try to mess with Buffy's life.

The First reemerged in season seven, using its ability to take on the form of anyone who has ever died to mess with Buffy's allies, as well as infiltrate her team by posing as a potential Slayer. The First and its minions, Caleb and the Harbingers, caused plenty of trouble for the Scooby Gang by trying to permanently open up the Hellmouth under Sunnydale High. Buffy's team thwarted the First's plan, closing off the Hellmouth and destroying Sunnydale in the process.

7 FAITH

Faith could really go on either a Great Goods or Big Bads list, and that is why she's such a fascinating character. Introduced in season three, Faith was the Slayer called into action after Drusilla killed Kendra in season two (Buffy herself died momentarily in season one, but we're getting to that in a bit). The rough-around-the-edges Faith often served as a mirror of what Buffy could have become had she not been lucky enough to have a loving mother and supportive network of friends. When Faith found that sense of family with the totally demonic Mayor, she switched sides and became one of Buffy's most formidable foes.

Faith returned without warning in season four, throwing Buffy's already spiralling life into even further chaos. Using a final gift from her dead father figure, Faith switched bodies with Buffy in an attempt to steal her life. The two got past that altercation and, after a rehabilitating stint in prison on the "Angel" spinoff series, Faith finally overcame her demons and returned to fight alongside Buffy in season seven.

6 SPIKE

William the Bloody was originally a nervous and foppish wannabe writer in Victorian England. All that changed when he ran into Angelus and his vampire gang; Drusilla sired William, turning him into Spike and creating one of the most feared vampires in "Buffy" mythology. Before Spike even showed up in "Buffy's" second season, he'd already killed two Slayers. His first Slayer kill came in China during the Boxer Rebellion, and another Slayer fell because of him in New York City the late '70s. Spike lived up to his reputation, surviving fight after fight with Buffy while constantly tormenting her.

Spike's destiny changed, though, after he got an anti-violence chip placed in his head by the Initiative. Spike slowly started helping the Scoobies, mainly because he wanted to fight something and he realized he could hurt demons. Spike's close affiliation with the team drew him closer to Buffy, leading him to develop an infatuation with her. That infatuation led him to assault Buffy, a dark development that urged him to seek out his soul and strive to become better.

5 DARK WILLOW

A founding member of Buffy's evil-thwarting gang, Willow Rosenberg grew from being a meek and mousy nerd to a confident witch over the course of "Buffy's" first five seasons. She even found happiness with the love of her life, Tara, as they helped save the world on a weekly basis alongside Buffy. Things took a dark turn for Willow in season six, though, as she began to rely more heavily on magic to get through her day to day life. She even used a spell to make Tara forget an argument they'd had.

While Willow was flirting with darkness through much of season six, she went fully evil after watching Tara die from a gunshot wound. Willow absorbed all the evil magic she could get her hands on and started off on a revenge mission to kill the Trio. She succeeded in flaying Warren and then turned her intentions up to apocalyptic levels. Only pleas from her best friend Xander, who proved his unconditional love for her by staying by her side, brought Willow back to reality and safety.

4 THE MASTER

"Buffy's" abbreviated first season introduced a bad guy that set the tone for all those who would follow after him. The oldest vampire ever introduced on "Buffy," the Master was so old that he had grown past having human features. His face and body were permanently distorted into the demonic look that all younger vampires could turn on and off. The Master didn't mind it, of course, as he was pure evil and purely theatrical. Unlike some of the more serious villains on this list, the Master relished his role as a bringer of chaos and torturer of souls.

"Buffy's" first season focused on the Master's desire to free himself from a mystical underground prison and slay the Slayer. The Master succeeded on both fronts, drowning Buffy and breaking out into Sunnydale. He didn't count on the Slayer having a friend (Xander) around to give her mouth to mouth, though, so he was surprised to see Buffy alive once more -- just as she threw him through the library's skylight, impaling him on a massive plank of wood.

3 GLORY

"Buffy" upped the stakes in season five by pitting the Slayer against a god named Glorificus ("Glory," for short). This rivalry also gave Buffy a new kind of villain to go up against, one that was cast out of her hell dimension and forced to take on the appearance of a well-off and well-dressed socialite. Glory's soft demeanor hid an incredibly powerful being, one whose powers included super strength and speed as well as invulnerability.

Glory's main mission was to go back home to her hell dimension by any means necessary. Those means meant using a mystical artifact known as a key (a.k.a. Buffy's sister Dawn) to open up a door to that hell dimension (one that could never be closed). Not only did Glory go after Buffy's literal flesh and blood, she also brutally attacked Tara's mind and terrorized all of the Scoobies, briefly driving them far away from their Sunnydale home. Armed with the hammer of a god, Buffy beat Glory back and prevented the destruction of Earth, but only by sacrificing herself in the process to close Glory's portal.

2 ANGELUS

Angel appeared in "Buffy's" first season, brooding and offering cryptic advice. Buffy soon learned that the mystery man she was crushing on was a vampire, but he was a vampire cursed with a soul so that his guilt would make feel the pain he had caused others over the years. Angel wanted to atone for his sins and fighting alongside Buffy seemed like a good way to do that. The two got too close, however, and one night of pure happiness together caused Angel's curse to wear off. Angel became Angelus again, setting the sadistically evil vampire loose upon the world.

Angelus teamed up with his old pals Spike and Drusilla and they assembled a genocidal demon. Angelus then became one of the few "Buffy" Big Bads to actually kill a member of the Scooby Gang, Jenny Calendar. Angel hunted her through the halls of Sunnydale High and snapped her neck for trying to reinstate his curse. Angelus' reign of terror came to an end thanks to the ill-timed one-two punch of Willow restoring his soul and Buffy knocking him into a hell dimension.

1 THE MAYOR

"Buffy" season three remains a fan favorite, perhaps because it features the charming and devious Mayor Richard Wilkins III. With the smiling persona of a germ-obsessed family man, the Mayor's regressive and uptight attitudes would have been enough to annoy Buffy and the teens of Sunnydale High. On top of being a stickler for the rules, the Mayor was also a two-hundred year old sorcerer hellbent on achieving a new level of power through the ritual of the Ascension.

Timed to coincide with graduation day, the Mayor prepared for his transformation into a giant, demonic hell-snake while fighting off the Scooby Gang every step of the way. He convinced Faith to switch sides, briefly kidnapped Willow and tried to turn Angel back into Angelus. He even gave his entire commencement speech to the graduating class before ascending, boring them with his words before turning into a giant beast. Upon his transformation, he ate Principal Snyder and killed many of Buffy's classmates. Buffy only managed to defeat the Mayor by making him chase her through the halls of Sunnydale, which were lined with explosives. With Buffy a safe distance away, Giles blew the Mayor straight to metaphorical hell.

Who are you favorite "Buffy" Big Bads? Let us know in the comments!