He is best known for his recurring roles on the television shows Deadwood, Lost, Sons of Anarchy and The Good Wife. Welliver was born in New Haven, Connecticut, the son of Norma Cripps, a fashion illustrator, and the landscape painter Neil Welliver.

He studied drama at New York University in the early 1980s, before his film and television career began to take off.

Welliver has worked on several film projects, including The Doors, Rough Riders, Mulholland Falls, Twisted, Biker Boyz, and Assault on Precinct 13.

He played Al Capone in the movie Mobsters, had a recurring role as a doctor on the television show NYPD Blue, and was one of the stars of the CBS police drama Brooklyn South. Moreover, Welliver is well-known for playing the semi-regular character Silas Adams on the HBO series Deadwood, as well as for his prominent role as Lionel McCready in Ben Affleck's Gone Baby Gone. He is a longtime friend of actor Laurence Fishburne, with whom he appeared in Fishburne's directorial debut Once in the Life.

Welliver played "The Representative" in two episodes of the popular series, Prison Break. He also portrayed Kyle Hollis (a.k.a. Reverend Orson Parker) in the NBC series Life. Welliver appeared in the season five finale of Lost as the "The Man in Black", the unnamed nemesis of Jacob (played by good friend Mark Pellegrino), and continued to portray this character during the sixth and final season.

He appeared as a guest star on episode two of season five of Supernatural, portraying "War". He was introduced into FX's Sons of Anarchy midway through season two, in which he portrays Irish gun kingpin Jimmy O'Phelan.

In 2009, he started playing the role of Prosecutor Glenn Childs, a rival of Chris Noth's character, in the CBS series The Good Wife.

Entertainers, Celebrity