From Wiktionary, the free dictionary
From Buffy + -ian.
Buffian (plural Buffians)
- (slang) A fan of the television series Buffy the Vampire Slayer.
2000 January 17, Rachel, “Re: Inaugural ACT Buffy Meet”, in aus.tv.buffy[1] (Usenet):Sorry to have missed meeting the Canberra Buffians.
2001 May 31, Forge [username], “Re: Wonky wins in Finale Ratings! Outraged DA fans demand recount!”, in alt.tv.buffy-v-slayer[2] (Usenet):In all this time it still hasn't occurred to you that Buffians couldn't possibly give less of a shit about ratings?
2002 June 2, Trin, “Re: ROLL CALL!”, in uk.religion.pagan[3] (Usenet):Yay - 'nother Buffian :D