In a story from|IHitFix, it seems that Kieran Culkin was recently cast as Wallace Wells in Scott Pilgrim vs. the World

Based on the Oni Press graphic novel, written by Bryan Lee O'Malley. Mary Elizabeth Winstead will play the dream woman of a young slacker (Michael Cera). But the only way he can win her heart is by battling and defeating her seven evil ex-boyfriends.

Culkin's character is Pilgrim's homosexual roommate who tries to help his friend win back the love of his life.