Daniel "Oz" Osbourne is a fictional character created by Joss Whedon for the television series Buffy the Vampire Slayer. The character is portrayed by Seth Green. Green also portrays the character in one episode of spin-off series Angel. In Buffy, Oz is portrayed as a taciturn, guitar-playing teen who becomes boyfriend to Willow, one of the show's main characters. After first appearing in the episode "Inca Mummy Girl", Oz discovers he is a werewolf in the episode "Phases" and becomes a recurring character throughout the second season. Green is elevated to main cast for the third season, and departs from the series in season four. Green portrays the character for a final time in the season four finale "Restless" as part of a dream sequence. The character made a brief canonical 'return', however, in the 2009 Buffy the Vampire Slayer Season Eight storyline "Retreat".