
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.

Law & Order
TV • 1990

Bones
TV • 2005

CSI: Crime Scene Investigation
TV • 2000

The Mentalist
TV • 2008

Criminal Minds
TV • 2005

The X-Files
TV • 1993

Boston Legal
TV • 2004

24
TV • 2001

Law & Order: Criminal Intent
TV • 2001

The Walking Dead
TV • 2010

The West Wing
TV • 1999

ER
TV • 1994

Supergirl
TV • 2015

Medium
TV • 2005

The Closer
TV • 2005

Miami Vice
TV • 1984

The A-Team
TV • 1983

The A-Team
TV • 1983