Buffy Summers is a '90s icon who paved the way for several supernatural shows such as Buffy The Vampire Slayer faced off against a plethora of paranormal threats and sacrificed everything — including her life — to defeat the vampires, demons, and the forces of darkness lurking in Sunnydale.
The villains of the Buffyverse are powerful entities who pushed the Slayer to the brink. Buffy's antagonists inspired the villains from The Vampire Diaries, many of whom Buffy could defeat — though some she would be powerless against.
Could Defeat: Katherine Pierce
Katherine is over 500 years old and a dangerously cunning vampire, but Buffy has faced worse. The evil doppelganger has the advantage of superior strength, speed, and compulsion. However, Buffy could utilize vervain weaponry to take her down as the vampires in The Vampire Diaries are exceptionally vulnerable to this herb.
In a cross-over situation, Buffy could confer with Alaric and build new weapons that could help her defeat Katherine.
No Chance: Silas
Silas is an exceptionally powerful psychic and the first immortal being in the world of The Vampire Diaries. He easily overpowers Elena, Caroline, and the Salvatore brothers, and proves to be more powerful than the Original family.
Buffy may have an advantage with Willow in her corner, although Silas proved capable of defeating witches when he attacked Bonnie Bennett. Without her friends, the Slayer is vulnerable and wouldn't stand a chance against the psychic.
Could Defeat: Damon Salvatore
Damon becomes a fan-favorite character early in The Vampire Diaries despite his initial debut as a series antagonist. The older Salvatore proves to be more dangerous than his brother when he kills Zach, turns Vicki into a vampire, and abuses Caroline.
Damon is younger than Katherine, however, and would be another easy opponent for Buffy to defeat. The Slayer could use vervain again or her trusty crossbow to take out the senior Salvatore brother.
No Chance: Sybil
Sybil sets her sights on the Mystic Falls gang in Season 8 of The Vampire Diaries and promptly establishes herself as one of the show's scariest villains. The cannibalistic Siren proves to have psychic powers even stronger than Silas' as she forces Damon and Stefan to do her bidding.
The Slayer's abilities are no match for Sybil's psychic powers. The Siren would likely lure Buffy to her demise using her formidable hypnotic skills.
Could Defeat: Elijah Mikaelson
Elijah is introduced as an antagonist in Season 2 before his role is usurped by his brother Klaus. The Original vampire is exceptionally strong and powerful, but his vulnerability to White Oak gives Buffy an advantage in battle.
Buffy could use a White Oak dagger to incapacitate Elijah or the White Oak stake to permanently kill him. Without his half-brother's werewolf DNA, Elijah is more susceptible to harm and could be taken down by the Slayer.
No Chance: The Heretics
The Heretics aren't the most popular villains in The Vampire Diaries but they are one of the strongest. The witch-vampire hybrids siphon magical power from their vampire blood and prove too powerful for the Mystic Falls gang to defeat.
Nora, Mary-Louise, Beau, Oscar, and Malcolm have vampire physicality and witchcraft at their disposal. Their combined strength would be too much for the Slayer to overcome.
Could Defeat: Esther Mikaelson
The Original witch is exceptionally powerful, but her magic is nothing that Buffy hasn't encountered before. The Scooby Gang has defeated witches in the past and with Willow at her side, the Slayer could defeat the matriarch of the Original vampire.
Esther would be unlikely to attack Buffy in a cross-over scenario, however. If anything, the Original witch would encourage Buffy to fulfill her duties by eliminating Esther's vampire family.
No Chance: Klaus Mikaelson
As a member of the Original family, Klaus is one of the oldest vampires in The Vampire Diaries and exceptionally strong and fast. He can compel other vampires as well as humans and his werewolf lineage makes him immune to the effects of the White Oak dagger.
Buffy could attempt to use the White Oak stake against Klaus, but the hybrid has both vampire and werewolf physicality. The Slayer would be overwhelmed in combat and vulnerable to Klaus' compulsion.
Could Defeat: Kai Parker
Kai is one of the most despicable villains from The Vampire Diaries. The sociopathic Siphoner is a powerful enemy but without a source of magic to draw from, he is vulnerable to the abilities of the Slayer.
Kai transitions into a vampire in Season 6, though he is quickly killed by Damon Salvatore. Buffy would be at a disadvantage against Kai the Heretic but could defeat him in his former human incarnation.
No Chance: Rayna Cruz
Buffy initially appears to be evenly matched with the Huntress, but Rayna Cruz has the advantage of the Phoenix Stone. If she marks Buffy, the Slayer will be forced to run from her continuously. If she kills Buffy, her soul is trapped within the stone forever.
Buffy could wear Rayna down, but the Huntress is relentless. Eventually her persistence would overwhelm the Slayer, and the Phoenix Stone would claim another soul.