Santoro is best known for his roles in "300" and "Love, Actually."

In "Morris," he will play a lover of Carrey's character, The Hollywood Reporter said.

Glenn Ficarra and John Requa, who wrote the dark comedy "Bad Santa," are directing the new film about a married father who is sent to prison and falls in love with his cellmate, played by Ewan McGregor.

"Knocked Up" co-star Leslie Mann will play the wife of Carrey's character, the trade paper said.