Alexander Harper Berkeley (born December 16, 1955) is an American actor. He is known for his television roles as Sheriff Thomas McAllister on the crime drama The Mentalist, George Mason on the political thriller series 24, Percy Rose on the action thriller series Nikita, the Man on The Booth At The End and Gregory in AMC's The Walking Dead. His notable film roles include Todd Voight in Terminator 2: Judgment Day, Agent Gibbs in Air Force One, Bowery Snax in Sid and Nancy, Dr. Lamar in Gattaca, Trevor Lyle in Candyman and Ralph in Heat.

Xander Berkeley

Acting Born December 16, 1955 Brooklyn, New York City, New York, USA

Alexander Harper Berkeley (born December 16, 1955) is an American actor. He is known for his television roles as Sheriff Thomas McAllister on the crime drama The Mentalist, George Mason on the political thriller series 24, Percy Rose on the action thriller series Nikita, the Man on The Booth At The End and Gregory in AMC's The Walking Dead. His notable film roles include Todd Voight in Terminator 2: Judgment Day, Agent Gibbs in Air Force One, Bowery Snax in Sid and Nancy, Dr. Lamar in Gattaca, Trevor Lyle in Candyman and Ralph in Heat.

Known For

The Mentalist

Sheriff Thomas McAllister

Law & Order

Clay Pollack

Criminal Minds

Det. Hyde

CSI: Crime Scene Investigation

Rory Atwater

Bones

Dr. Bancroft

24

George Mason

The Walking Dead

Gregory

Law & Order: Criminal Intent

George Pagolis

The X-Files

Dr. Hodge

The West Wing

Franklin Hollis

ER

Detective Wilson

The Closer

Detective Curt Landry