Air Date: 10/26/99
The Joss Whedon cult classic series did a Halloween story every two seasons, and while the first two are both considered essential Halloween TV-episode viewing (the third suffers from Annoying Kid Sister Syndrome), when it comes down to it the best of the bunch is undoubtedly the fourth season offering, "Fear, Itself."
The episode comes along at the beginning of the gang's first year in college, conveniently at a time where self-doubt is eating away at everyone. Perfect timing then, for a bunch of idiot frat guys to copy a pentagram from an actual spellbook while setting up their haunted house party. The house comes alive, and all of the spooky decorations with it, trapping everyone inside and splitting up Buffy and pals to battle the manifestations of their innate fears while a demon feeds off of it, gradually gaining the strength to enter their world.
Despite its age, "Fear, Itself" doesn't feel dated at all, and manages to throw in zombies, homicidal skeletons, talking severed heads, and a bowl full of eyeballs while connecting on a character level as well. Plus, Giles cuts through the entire house with a chainsaw, and the episode ends with a hilarious visual gag that's never not funny.