Seth Green to Play a Creepy Guy Named Daryl on 'How I Met Your Mother'

On Friday, How I Met Your Mother used its official Twitter account to announce that Seth Green would guest star on the sitcom in December. Green will be reunited with his former Buffy the Vampire Slayer co-star Alyson Hannigan, who plays Lily Aldrin on HIMYM. CBS has yet to release any official press release about Green, so at this time, this is all the information that's out there about Green's episode or episodes.

Green will be one of many guest stars on what could possibly be HIMYM's final season. In August, it was announced that former Saturday Night Live castmember Abby Elliott would join the show for a multi-episode arc as a crazy girl who Ted Mosby probably dates.