Xanderista

plural Xanderistas

1. A fan of the character Xander Harris from the television series Buffy the Vampire Slayer.

   I used to be a major Xanderista. But this season, he's bugged me a lot.

   1999 April 11, QueenChase [username], “Re: Who does Xander Love?”, in alt.tv.buffy-v-slayer (Usenet)

   2 more examples

   Victoria P. is a staunch Xanderista, and will take Xander's part in almost any discussion, even when she knows he is wrong.

   2000 June 7, vicpusateri [username], “Re: OT: Challenge to Regulars”, in alt.tv.buffy-v-slayer (Usenet)

   I recall that Xanderistas did react in the way you describe, even coining the term "Xander Slander".

   2003 February 11, Rose, “Re: So Xander has (Spoilers for "First Date")”, in alt.tv.buffy-v-slayer (Usenet)