My favorite show ever, so I feel obliged to type the characters -
Buffy - ISFP (Buffy's nearly always typed as an SFP. ISFP feels better for me cognitively as well as behaviorally, as Fi moderated by Se feels better than Se moderated by Fi. Plus Buffy is behaviorally an introvert)
Willow - INFP (This one is really difficult. Willow seems Ni > Ne but Fi > Fe. What clinched INFP was remembering her beautiful soliloquy to Buffy at the end of Season Three (
Graduation Day pt I?), when she broke it to Buffy that she was staying in Sunnydale for college, instead of Oxford/Yale/MIT/wherever she wanted, to fight the Hellmouth with Buffy. Screamed Fi dominant.)
Xander - ENTP (I''m not too sure about this one. ENFP seems just as likely. Ne-Ti/Fi seem equally good.)
Giles - INTJ (Not much argument here.)
Angel - ISFJ (Angel on Buffy is more of an Si-dom with his focus on the past, while Angel on Angel is more of an Ni-dom, what with making himself into a Batman-style Ni symbol/abstraction. Since this is Buffy, I'll go with ISFJ. Either way, he's Fe-overload. SO MUCH Fe.)
Spike - ESFP (Some days I think Spike is an ENFJ, some days I think he's an ESFP. His selfless devotion to Drusilla, then Buffy makes me think Fe-Ni, but
Fool for Love and
Touched, his big character moments, make me think Se-Fi.
"I don't have a reputation for being much of a thinker, I usually go by my blood. Which doesn't always flow in the direction of my brain." Oh SPIKE!)
Dawn - ENFP (Dawn is a lot like Xander in cognition, clearly Ne-dom.)
Anya - ESTJ (Devotion to business, great aptitude for it, love of money, desire to know human customs is Te-Si.)
Cordelia - ESTJ (Classic social climber, but not in an Fe-way. She has a great grasp of organization and a talent for networking, which we see more of on Angel.)
Riley - some sort of SF, but I mean...it's Riley. I'll give you ESFJ today.
Joyce - ISFJ (Joyce is frequently in reaction mode to events that have already happened, which screams Si. She's clearly an Fe user as well as a quintessential mother hen. Joyce is the shit, though.)
Jenny - ENTJ (Sly, sharp-witted, tough as nails.)
Oz - INTP (Oz's sardonic, hilarious barbs show aux Ne and stoicism, detachment, and mixture of deep intelligence and passive nature show Ti-Ne.)
Tara - INFJ (Tara is frequently the first to jump to understandings and realize hidden patterns (especially with regards to magic, which is...well...mystical), and has an exceptionally deep conceptual and context-independent grasp of magic and the universe, deeper that that of the extraordinarily powerful Willow, which make her Ni-dom. She and Giles (the Ni-doms in the group) are the only ones to realize what magic will truly do to Willow. She was what helped me type Willow as INFP instead of INFJ. Tara is also THE SHIT.

)
Wood - INTJ (Wood thinks of himself as a symbol as well. He doesn't have a very firm sense of self-identity outside of the roles he plays - principal, bad boy, evil fighter. In a way, he's like a human mixture of Spike and Angel. Really interesting character, one whose type I question.)
The Master - INTJ (Classic INTJ villain.)
Angelus - ENTJ (Angelus is different from Angel in a way that Spike is not from William.)
Drusilla - ENFP (The quintessence of an Ne-dom.)
The Mayor - ESFJ (His Fe devotion to Faith/avuncular nature and his being seeped in Sunnydale tradition/being very traditionally minded make him a pretty obvious ESFJ.)
Faith - ESTP (This is a crystalline typing. She's hella Se-dom. She totally gets Spike in this way.)
Maggie Walsh - INTJ (Yawn.)
Adam - INTP (Yawn x2.)
{
Season 4 was the great wasted season of Buffy, but that's a tangent for another time. Adam and professor Walsh both had amazing potential that was mostly wasted.}
Glory - ESFJ (semi-yawn x3, but S5 is still my favorite season.)
Warren - ENTJ (Outside of his antisocial nature and amorality, he's crafty, resourceful, and scheming, and a superb villain.)
The First - LOLZ