Lea was born in British Columbia and his first major role was on the TV series The Commish where he played Officer Enrico Caruso from 1991 to 1994. It was during this time that he had a minor guest role in a first-season episode of The X-Files called Gender Bender.
The producers were impressed by his performance and when, in the second season, he auditioned for the role of turncoat FBI agent Alex Krycek, he was successful. Lea guest starred in twenty-four episodes from 1994 to 2002 and became a popular character amongst the fans. Because of his character's willingness to switch sides, he was known as the 'ratboy'. Since the X-Files he has had several recurring roles on television. He was bad guy Tom Foss on ABC Family's Kyle XY and just finished guest-starring on the ABC show, Men in Trees, opposite his real-life girlfriend (since 2001), Suleka Mathew.