Buffy the Vampire Slayer aired its first episode in March of 1997, and more than twenty years later, fans still are in raving about how amazing the series is. There are plenty of reasons to love Buffy from its awesome choreographed fight scenes to the unique style of smart dialogue that series creator Joss Whedon specializes in.
One of the main reasons for the show's success is its amazing cast. In the series, strength is definitely an asset in many situations. But as we came to learn, it was one's smarts that saved the day a lot of the time. So, here are all the main characters ranked by intelligence.
Xander
Xander Harris is a high school guy who befriends Buffy Summers almost immediately after she starts attending Sunnydale High. He becomes one of her closest friends and a key part of the Scooby Gang (as the group call themselves).
Xander has many great qualities. He's funny, loyal, and willing to stand up for those he cares about, even when he knows he's going to suffer possibly life-threatening consequences for doing so. Unfortunately for him, he is also a bumbling fool. When he opens his mouth, it is usually to stick his metaphorical foot in. Thankfully, his big heart more than makes up for his small mind.
Faith
The Slayer is summoned once every generation, a teenage girl destined to fight the forces of darkness. When Buffy dies at the end of the first season, she is thankfully revived. However, as the Slayer has died, a new one named Kendra steps up to fulfill the duties destiny demands. After Kendra is also killed, the next Slayer to surface is Faith.
There is a lot to love and a lot to hate about Faith. She's fiercely independent and a courageous young woman who knows how to take care of herself. Or, she thinks she does. In truth, her bravery and independence cover her deep fears, often manifesting as recklessness that endangers others around her. It's easy to be brave for someone too dense to see the consequences of her actions.
Spike
Formerly known as William the Bloody, the vampire Spike is one of the most deadly of his kind to ever live (or to enjoy unlife, to be more precise). Angel turned him into a vamp back in 1880 and the two of them traveled the world along with their respective paramours, Drusilla and Darla. Since becoming a bloodsucking immortal, he's even killed two Slayers.
While Spike starts off as a downright menacing villain, he quickly becomes a bit of a joke, especially after getting dumped by Drusilla. A bit later he's captured and implanted with a chip that renders him harmless. The fierce tactician who killed Slayers for sport is left as little more than a heartbroken blonde wimp who occasionally sings punk songs.
Dawn
While Spike becomes dumber as the show progresses, Dawn Summers is introduced as a dumb younger sister to Buffy, a little girl whose immaturity is representative of her age. However, while Spike regresses, Dawn grows wiser with time.
Dawn Summers is a very polarizing character. Her first appearance is at the end of the first episode of the show's fifth season. How does a character like Buffy have a sister who only makes an appearance after four seasons of the show have come and gone? Because Dawn is a character retconned into existence--a non-human entity who assumes a human form and makes false memories of a shared past for herself and those around her. Such a convoluted introduction is one of several reasons fans dislike her.
Buffy
As the "Buffy" part of Buffy the Vampire Slayer, the titular protagonist has a lot of responsibility riding on her shoulders. School, homework, dating, and the fate of the world are just some of the things getting in the way of her having a perfectly normal social life.
Like many teenagers, she's more interested in socializing than what dusty old scrolls say about the forces of evil. Despite her reluctance to study, Buffy demonstrates an innate ability to think on her feet and notices minuscule details. She also gets smarter with age. When she and her genius friend Willow attend college together, Buffy actually manages to make Willow jealous of her academic achievements at one point.
Cordelia
If Buffy is casually shallow, Cordelia Chase is as deep as an empty bottle of Chanel N°5. Cordelia is both a rival and ally to Buffy at different points, being just as likely to help the Slayer out as to publicly disgrace her in front of the school (a fate far worse than being eaten by hordes of the undead).
While Cordelia is more vain and petty than Buffy, she is also smarter. She definitely comes across as an airhead, but she has natural leadership abilities and does well on her SATs. Plus, there is a lot of genuine thought that goes into dressing that well and keeping up with all the changes of what's fashionable.
Angel
As the only vampire with a soul, Angel has dealt with a lot in his long unlife. He can't kill people to feed on their blood without feeling remorse for his prey, while he lives with the guilt of all the horrible ways he used to torture his victims over the centuries.
In the modern era, he helps the Scooby Gang fight other actually-evil vampires. More importantly, he's Buffy's first true love. Unfortunately, he can't be physically intimate without losing his soul again and becoming a sadistic monster. At the end of the third season, he leaves Sunnydale to head off on his own. Still, there's no denying that whether he's fighting the forces of darkness or leading them into battle, Angel has a keen mind coupled with the wisdom of age.
Oz
Oz is a musician, a werewolf, and Willow's first real boyfriend. He's also a man of few words, his brilliance expressed with a stoner-like monosyllabic simplicity.
Despite seldom showing it, Oz is a genius. He and Willow are both approached in high school by people interested in recruiting them to work for some of the world's leading software developers. This is particularly impressive since Oz never studies, embracing a zen-like state as he lets his homework take care of itself. Such negligent habits do force him to repeat his senior year of high school, though that may be a strategy to get more time with Willow.
Willow
Like her boyfriend Oz, Willow Rosenberg is a bonafide genius. She studies hard and frequently tutors her friends and peers to help them succeed. After Angel kills her teacher Jenny Calendar, she takes over teaching Ms. Calendar's class while still just a high school student.
While it is unclear whether Willow or Oz is inherently smarter, Willow applies herself more and so surpass his academic records, gaining her choice of colleges to choose from. She also learns hacking and teaches herself enough magic to be able to perform impressive spellwork as a witch.
Giles
As the librarian of Sunnydale High School, one would not expect Giles to be so stereotypically... librarian-y. With his prim English accent, old books, thick spectacles, and knowledge of dead languages, Rupert Giles is a walking stereotype of what lazy TV writers in the '90s thought intelligent British people were like. For all that, he's still one of the smartest--and most interesting--characters on the show.
Once known as Ripper, Giles studied black magic as a youngster before cleaning up his act. As Buffy's Watcher, he serves as both a surrogate father figure and a mentor, teaching her all she needs to succeed as the Slayer. Whether he's deciphering an incantation in a dusty grimoire or poring over texts for obscure details about demonology, Giles always finds an answer to the problems at hand.