Stephen Root has been cast as a regular opposite Bill Hader and Henry Winkler in Hader’s HBO comedy pilot Barry.

The project, co-written and directed by Hader, centers on an ex-Marine (Hader) who works as a low-rent hitman in the Midwest. Lonely and dissatisfied in his life he begrudgingly travels to Los Angeles to kill someone and ends up finding an accepting in a group of eager hopefuls within the L.A. theater scene.

Root will play Fuches, a lawyer who arranges Barry’s hits. Also co-starring in the pilot are Sarah Goldberg, Glenn Fleshler and Anthony Carrigan.

Root is in business with HBO — he plays J. Edgar Hoover in the network’s movie All the Way.  He is repped by Gersh and Brillstein Entertainment Partners.