David Gallagher’s film debut was as the role of Mikey in the sequel Look Who’s Talking Now (1993). In 1995 he played in a stage production of A Christmas Carol. His next film was in 1996 with John Travolta in the movie Phenomenon. Later that year, he was cast as Simon Camden in a new family drama series 7th Heaven. During his time on 7th Heaven, Gallagher became a teen idol. He shot a few movies during hiatuses from filming, including the direct-to-video Richie Rich’s Christmas Wish and Little Secrets. During 7th Heaven‘s 8th season (2003), Gallagher left the show and attended college full-time. He returned to the series part-time during season 9 and for what was thought to be the 10th and final season. The show was unexpectedly picked up for an 11th season, but Gallagher opted not to renew his contract, for reasons that are unknown, although it has been speculated that the cast pay cut may have been a big factor in Gallgher’s absence.Gallaghers’s first role after leaving 7th Heaven was an apperane on Numb3rs, playing serial killer Buck Winters in September 2006, a role in which he reprised in January 2009.