Buffy Summers dies multiple times throughout Buffy the Vampire Slayer, but each time Buffy manages to return from the dead. Played by Sarah Michelle Gellar, Buffy has a complicated relationship with death, which is intimately connected with her role as the slayer. It should be no surprise then, that Buffy herself has died three times during her tenure.
Throughout Joss Whedon's Buffy the Vampire Slayer, Buffy repeatedly avoids dying at the hands of various evil forces. However, she does succumb three times, and they have drastic ramifications for the series. From ancient prophecies to gunshot wounds, Buffy might die, but she always comes back.
1 Season 1, Episode 12, "Prophecy Girl"
Buffy dies for the first time in Buffy the Vampire Slayer season 1, episode 12, "Prophesy Girl." Giles learns of an ancient prophecy in antique watcher text (the Pergamum Codex) that the vampire slayer will face and die at the hands of season one Big Bad, The Master. Indeed, when Buffy confronts The Master, he bites her neck and leaves her unconscious, face down in a shallow pool of water. Thankfully, Xander and Angel arrive soon after and revive her.
Buffy is saved from drowning by Angel and resuscitated by Xander, who performs R on her. Buffy quickly spits up mouthfuls of water and returns from the dead with newfound strength and focus. Moments before killing her, The Master taunts Buffy by informing her that it is Buffy's blood which allows The Master to reach full strength and escape his underground prison - this is not mentioned in the Pergamum Codex. Ironically though, Buffy only gains the requisite strength to defeat The Master after he has killed her.
2 Season 5, Episode 22, "The Gift"
Buffy's second death in Buffy the Vampire Slayer is perhaps her most famous. In season 5, episode 22, "The Gift," Buffy throws herself to her death to save the world, or more specifically, her sister, Dawn. Dawn was introduced in season 5 as the human form of a mystical energy called the Key. By spilling Dawn's blood, the barriers between Earth and an infinite array of hell dimensions are dissolved, and only stopping the blood will cease the carnage. Earlier in the season, Buffy is bestowed cryptic advice by the first vampire slayer, who states that death is Buffy's gift.
Buffy subsequently discovers that Dawn was created from her blood, and, finally understanding her "gift," sacrifices herself. This death in season 5 was supposed to spell the end for Buffy the Vampire Slayer but when further seasons were ordered, Whedon resurrected Buffy once more. This time, Willow, Xander, Tara, and Anya cast a resurrection spell by invoking the Egyptian god Osiris during season 6, episode 1, "Bargaining." Willow endures a series of trials to accomplish the spell, which the Scoobies believe initially to have been unsuccessful. Resultantly, she awakens in her coffin and Buffy must live through her nightmares by crawling out of her own grave.
3 Season 6, Episode 20, "Villains"
The third and final time Buffy dies in Buffy the Vampire Slayer was in season 6, episode 20, "Villains," after being shot by Warren in the previous episode, "Seeing Red." Buffy is rushed to hospital with a deep chest wound, where doctors try frantically to save her life. Willow, distraught from Tara's death only moments earlier, arrives at the hospital in full Dark Willow mode, just as Buffy flat lines. There is some debate whether Buffy dies at this moment, or if this was interference from Willow's powers which cause the electronics in the room to go haywire.
But whether caused by Warren or Willow, Buffy's heart does stop beating, and it appears she would have died without Willow's interference. The super-charged Willow heals Buffy's wounds with her magic and draws the bullet out from her chest - pocketing it to torture Warren with it later. Buffy recovers immediately, contrasting starkly against Willow's futile attempts to revive Tara.
A version of Buffy also dies in the alternate dimension colloquially known as the Wishverse. In Buffy the Vampire Slayer season 3, episode 9, "The Wish," Anyanka (still a vengeance demon) fulfills Cordelia's wish that Buffy had never come to Sunnydale. Consequently, vampires, led by The Master, have overrun the town. Later, Buffy does arrive in Sunnydale but is killed by The Master, who effortlessly snaps her neck. Many have proposed that this is the true fulfillment of the Pergamum Codex, and ultimately, Cordelia rescinds her wish, and Buffy the Vampire Slayer returns from the dead once more.