Sean Maher is an American actor. He debuted as the titular character on the show Ryan Caulfield: Year One in 1999. In the 2000s, he played Adam Matthews on Party of Five. He next starred as Chris McConnell on the TV series The $treet. He next became known for his role as Dr. Simon Tam on the sci-fi series Firefly, which he reprised in the movie Serenity. In the 2010s, he starred as Sean Beasley on The Playboy Club. At the same time, he had a recurring part as Marcus on Make It or Break It. He next played Mark Scheffer / Shrapnel on Arrow.