Reed Edward Diamond (born July 20, 1967) is an American actor. He most recently appeared in the NBC series Journeyman as Jack Vasser, the main character's brother.

Reed Edward Diamond was born in Brooklyn and raised in New York City. Attended the University of North Carolina at Chapel Hill before studying acting at The Juilliard School. He currently lives in Los Angeles and is married to actress Marnie McPhail.

Diamond was born and raised in New York City. He attended school at UNC-Chapel Hill and then went on to study acting at The Juilliard School in New York. His professional career began in 1990 with his co-starring role in the movie "Memphis Belle." Following that he appeared on Broadway, and in many television movies, and guest-star roles on TV. He is probably best known for playing Detective Mike Kellerman on the critically acclaimed NBC television show "Homicide: Life On The Street." Diamond most recently guest-starred on television in, "October Road," "Ghost Whisperer," "Vanished," "Without a Trace," "Numb3rs," "Law & Order," "CSI," "Medium," "The West Wing," "Judging Amy," "Crossing Jordan," "The Shield." Some of his most notable movie credits include "Good Night, and Good Luck," "Spider-Man 2" and "S.W.A.T." Diamond resides in Los Angeles with his wife, actress Marnie McPhail.