Mary-Kate Olsen as Tara courtesy Cliff Lipson/ Showtime Mary-Kate Olsen as Tara courtesy Cliff Lipson/ Showtime

Having (re-)proven herself last season on Weeds to be a bubbly little actress when she can tear herself away from the party/swarthy guy circuit, Mary-Kate Olsen next will guest-star on ABC's Samantha Who?

Appearing in one of Season 2's early episodes, MKO will play a self-destructive bad girl who reminds Samantha of her younger self. As such, Sam decides to take on MKO's hellion as a "fix-it" project, says an ABC rep. Olsen's gig first was reported by E! Online. - Matt Mitovich

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