10. Vampire Willow & Xander (Buffy The Vampire Slayer)
In the Buffy episode "The Wish", Cordelia - whilst holding Anya's Vengeance Demon necklance - says "I wish Buffy Summers had never come to Sunnydale." Anya, in her demon visage, says "done" and there is a sudden flash of bright light. Cordy finds herself in a new reality - which she is pleased about at first - but finds that lots of students are missing and that there is a curfew in Sunnydale each night (obviously because, without Buffy, vampires are running wild). Cordy also finds out that Willow and Xander are dead, which shocks her. However, she runs into Xander and Willow later and they seem very much alive. However, the two of them act much different to normal, far more confident and are also dressed in leather, which is also unlike them - they're vampires. In this "Wishverse" (as it became colloquially known), Xander and Willow are the Master's favourite minions and have been torturing Angel and brutally killing any human they come in to contact with. Vampire Willow would also reappear seven episodes later in "Doppelgängland".