EXCLUSIVE: Michael Zegen, who recurs as infamous mobster Bugsy Siegel on Boardwalk Empire, has been added to the cast of another HBO series, Lena Dunham’s comedy Girls. The network is keeping details about his character and the number of episodes he will appear in under wraps, but Zegen may fill the void left by the sudden departure of Christopher Abbott. He’ll also be returning to Boardwalk Empire this fall. Most recently, Zegen appeared alongside fellow Girls actor Adam Driver in Noah Baumbach’s Frances Ha. Zegen’s previous recurring gigs include The Walking Dead, Rescue Me and HBO’s How To Make It In America. He is with UTA and manager Jill Kaplan at Principal NY.