Frasier - "Room Full of Heroes"
Frasier featured a handful of Halloween-themed episodes, but "Room Full of Heroes" was notable for having the main characters dress up as their own personal heroes for Frasier's costume party.
However, things quickly went south when Niles showed up dressed as Martin and nobody would follow Frasier's tedious evening schedule. But, hey, with Roz as Wonder Woman and Daphne as Elton John, the party was bound to liven up.
Watch "Room Full of Heroes" (Episode 6, Season 9 of Frasier) on CBS All Access.