Buffy the Vampire Slayer was around for seven seasons, and each year, there was a big bad that Buffy and her Scooby Gang had to defeat. However, not all villains are created equal. Through the years, Buffy fought demons wanting to open Hellmouth, monsters that wanted to rule the world, and two close companions turned bad.
Each season finished with Buffy and her friends overcoming the Big Bads of the season, although some of the battles came with high casualties. The most villainous of the Big Bads took down beloved characters with them, while the most heroic was able to come around in the end and become heroes when all was said and done.
Dark Willow (Season 6)
Willow Rosenberg was one of the Scooby Gang's most heroic members, although there was always darkness boiling under the surface. That darkness rose in Season 5. Willow started to become addicted to magic and started to push the boundaries and use it excessively. She even used it to alter her own friends' memories.
Then, when Warren Mears accidentally murdered Tara, Willow went dark and became the Big Bad of Season 6. Buffy had no chance, but it was Xander who used their close friendship to bring Willow back. Willow rehabilitated and became a stronger hero in the end.
Spike And Angelus (Season 2)
in Season 2, there were two major Big Bads. Spike and Drusilla were the main antagonists for Buffy for much of the season throughout most of the season. However, soon Buffy's boyfriend Angel and Buffy consummated their relationship. Since his curse wouldn't allow happiness, he turned back into Angelus and became the ruthless main Big Bad of Season 2.
He was overly powerful, and it took Willow's magic to give Angel his soul back, but Buffy had to kill him anyway to save the world. Angel eventually returned, and both Angel and Spike became heroes in the end.
The Mayor (Season 3)
In Season 3, it was Buffy and the Scooby Gang taking on the Sunnydale mayor. The mayor was Richard Wilkins, who had served in the role from the time that Sunnydale started up until his fall. He was the Big Bad who was a sorcerer who wanted to become an actual demon.
The Mayor founded Sunnydale in 1899, and when he found the Hellmouth, he struck a deal with the demons to allow him to live. The Mayor became immortal and finally prepared for his ascension by taking over the vampire population. He teamed with Faith but was eventually beaten before he could ascend.
Adam (Season 4)
The Big Bad of Season 4 was created by a group called The Initiative. In the season, Buffy was dating a guy named Riley, and she ended up meeting and working with The Initiative upfront. The group is a U.S. Government agency that knows demons exist and capture them for research purposes.
They tamed Spike with an implanted chip and then tried to kill Buffy since she wouldn't stop asking questions. This led to Adam, a Demonoid created by the Initiative, taking control and planning to create a new race of creatures created by men, demons, and machines.
Glory (Season 5)
The Big Bad in Season 5 was Glorificus, known by most fans as Glory. She also has some nicknames, which shows how dangerous she really is, including The Abomination, The Beast, and That Which Cannot Be Named. She is a goddess from a hell dimension who was banished to Earth in human form.
Glory ended up as one of the most dangerous Big Bads that the Scooby Gang ever faced. She ruled over Hell with two other entities, but she grew more powerful and frightening, so the other two started a war and banished her to Earth. Her only goal was to find the Key to get her back, which would release Hell on Earth, but the Key ended up as Dawn Summers.
The Master (Season 1)
The first-ever Big Bad on Buffy the Vampire Slayer was the Master. He was the oldest vampire on record and one of the most powerful and respected of the entire race. There was a cult that worshipped him and wanted to bring him back to Earth.
He eventually sired Darla, which is who sired Angel. How powerful is the Master? He is one of the few beings who killed Buffy Summers, although she repaid the favor later. He is pure evil and wanted nothing more than to bring Hell to Earth and rule over wit with his vampire army.
The First Evil (Season 7)
Before he appeared on Firefly for Joss Whedon, Nathan Fillion was part of the Buffy the Vampire Slayer cast as the human form of The First Evil. When ranking the Buffy Big Bads based on villainy, it is a no-brainer to put The First Evil in the number one spot.
This is the personification of all the evil that exists on Earth, and it can take the form of a dead person to get others to follow its lead. In Season 7, it was Fillion's zealot-styled preacher named Caleb that served as its host. It is also the most powerful of the Big Bads because even though Buffy and her allies won in the end, they couldn't eliminate The First Evil.