The short Jeffrey Dean Morgan Shameless appearance has confused both viewers of the show and followers of the actor, and it seems confusing how the Walking Dead star’s character only appeared for a single episode. Jeffrey Dean Morgan is best known for playing Negan on The Walking Dead. Negan’s introduction is one of the most infamous sequences in the entire show and features the gruesome demise of two fan-favorite characters. Negan is far from Morgan’s first scene-stealing performance though. Morgan played The Comedian Zack Snyder’s Watchmen, broke many hearts on Grey’s Anatomy as Denny Duquette, and played John Winchester on Supernatural. He also briefly appeared on Showtime’s dramedy Shameless in 2011.