Initially signed for just six episodes, former Prison Break star Robert Knepper has been promoted to a series regular on Heroes.

Knepper will play Samuel on season four of the show, "the reluctant ringleader of a carnival," as the actor explained at the San Diego Comic-Con festival last week.

In the wake of his brother's passing, Knepper added that Samuel "made a decision that his life is not going to be the way it used to be," as he "one-by-one lures the heroes into helping with" this new plan.

Check out the incredible-looking volume five trailer for Heroes to watch this character in action.

Matt Richenthal is the Editor in Chief of TV Fanatic. Follow him on Twitter and on Google+.