Buffy is a American horror fantasy action film written and directed by Joss Whedon with Drew Gars as producer. It is a continuation of Whedon's 1996 WB/UPN horror fanasty television series Buffy the Vampire Slayer and stars the same cast, taking place after the events of the final episode and the continuation comic book series.
- Sarah Michelle Gellar as Buffy Summers, "The Slayer", one in a long line of young girls chosen by fate to battle evil forces in the form of vampires and demons.
- Alyson Hannigan as Willow Rosenberg, one of Buffy's best friends. She is a lesbian and a powerful Wiccan.
- Nicholas Brendon as Xander Harris, one of Buffy's best friend. He provides comic relief as well as a grounded, everyman perspective in the supernatural Buffyverse.
- James Marsters as Spike, a platinum-blond yobbish English vampire with a soul.
- Michelle Trachtenberg as Dawn Summers, Buffy's younger sister.
- Anthony Stewart Head as Rupert Giles, a Watcher and a member of the Watchers' Council, whose job is to train Slayers.
- David Boreanaz as Angel, a vampire, formerly known as Angelus, was a cruel killer until he was re-ensouled by a Romani curse.
- Tom Lenk as Andrew Wells, a reformed "super villain", a member of the Scooby Gang and a former Watcher.
- Jennifer Lawrence as Darcie Wendrake, a rogue Slayer who is actually a half-human half-demon hybrid. She plans on releasing an evil god like entity called Vortyxus that will destroy all of mankind after her being shunned by humanity.
- Djimon Hounsou as Balazhor, a ancient demon that was locked away in a temple who was once the general to the army of an evil god like entity called Vortyxus. He is set free by Darcie Wendrake and becomes her subordinate when she wants to release Vortyxus due to humanity shunning her.
- Emma Watson as Lisa Mercury, a girl that Darcie used to babysit when Lisa was little and partner in crime. Although she is the only human that Darcie trust since humanity shunned Darcie, she is sympathetic whenever she sees Darcie go too far in her antics.
- Liam Neeson as Thaddeus Thryce, Darcie's former Watcher. Thryce was Giles' former classmate from college.
- Ken Watanabe as Theophilus, a priest and the keeper of magic scrolls.
- Samuel L. Jackson as Martin Spencer, a CIA field operations officer.
- Rob Riggle as Vance 'The Grim Reaper' Liscio, a magic potion dealer and a businessman. He is Darcie's informant to the Magic underground.
- Iyari Limon as Kennedy, a Slayer and the head of Deepscan, where members of the rich elite hired Slayers as bodyguards, either for demon-related protection or non-demon related protection.
- Leonardo DiCaprio as Detective Robert Dowling, the leader of the San Francisco Police Department Vampire Task Force. He was an ordinary homicide detective until a case involving vampires brought him into contact with the Slayer, Buffy Summers.
- Idris Elba as Eldre Koh, a Nitobe Demon and a member of the Nitobe race.
- Amber Stevens as Anaheed, one of Buffy Summers' roommates in San Francisco and a Slayer.
- Amber Benson as Tara Maclay
- Emma Caulfield as Anya Jenkins
- Kristine Sutherland as Joyce Summers
- Andy Umberger as D'Hoffryn
- Charisma Carpenter as Cordelia Chase
- Alexis Denisof as Wesley Wyndam-Pryce
- Sarah Hagan as Amanda
- Felicia Day as Violet
- Indigo as Rona
- Dania Rameriz as Caridad
- Mary Wilcher as Shannon