James Marsden and Brazilian model, Rose Costa welcomed baby boy, William Luca Costa-Marsden, Los Angeles on Friday (Dec. 14)
Marsden briefly dated Costa after his split from wife Lisa Linde after eleven years of marriage in 2011.
According to People, the 30 Rock actor picked the name and is being very supportive.
His rep coud not be reach for comment.
He is already dad to daughter Mary James, 7, and son Jack Holden, 11, with Linde.