Jason O'Mara joins 'Agents of S.H.I.E.L.D.' ensemble for Season 4

LOS ANGELES, Aug. 1 (UPI) -- Irish actor Jason O'Mara has joined the cast of Agents of S.H.I.E.L.D. for Season 4, Marvel announced Monday.

The Vegas, Life on Mars, Terra Nova and The Good Wife alum will play the S.H.I.E.L.D. organization's new leader, taking over the post vacated at the end of Season 3 by Phil Coulson, played by Clark Gregg.

"Bringing Jason into the mix as the new director of S.H.I.E.L.D. forces everyone, particularly Coulson, to reevaluate their role in the agency," Jeph Loeb, executive producer and Marvel's head of television, said in a statement. "Jason has both the physical presence and acting dynamics that will connect with and challenge even the most loyal agent."

The show is to return to ABC on Sept. 20.