He is possibly best known for his portrayal of Cassidy "Beaver" Casablancas in the Teen neo-noir television series Veronica Mars, and for guest-starring in teen sci-fi drama Smallville as superhero Bart Allen, an adaptation of the character of The Flash and Impulse comic book. He is also well known for portraying Reed Garrett, Mac Taylor's stepson, on CSI: NY beginning in 2006, and for his roles in the horror films The Haunting in Connecticut, Jennifer's Body and the remake of A Nightmare on Elm Street.
Kyle Gallner was born in West Chester, Pennsylvania. He started his career by following his sister along to one of her auditions.
Perhaps best known for his role as Cassidy "Beaver" Casablancas on the CW's lone hit series, "Veronica Mars" (2004- ), actor Kyle Gallner had been appearing in films and on television since his early adolescence. Born on Oct. 22, 1986 and originally from Philadelphia, PA, Gallner made his first screen appearance on an episode of "Third Watch" (NBC, 1999-2005). After making his feature debut with a small role in the bizarre Michael Showalter comedy, "Wet Hot American Summer" (2001), he returned to television with episodes of "Law & Order: Special Victims Unit" (NBC, 1999- ) and "Touched By an Angel" (CBS, 1994-2003), playing the witness to a hit-and-run of a prostitute reluctant to give up his friend as the murderer in the latter. He next appeared in the series finale of "The District" (CBS, 2000–04) before playing his first recognizable role - that of Bart Allen (a.k.a. "The Flash") on "Smallville" (CW, 2001- ) during the 2004-05 season.
In 2005, Gallner joined the cast of "Veronica Mars" for the last three episodes of the first season, giving him the opportunity to carry over his role of Beaver into the next season - a role which depicted him as a needy and emotionally neglected, but nonetheless nefarious perpetrator of a heinous bus crash, among other dastardly deeds. During his run on "Veronica Mars," Gallner continued making guest spots, appearing in episodes of "Jack & Bobby" (WB, 2004–05), "Cold Case" (CBS, 2003- ), "CSI: New York" (CBS, 2004- ) and "Bones" (FOX, 2005- ). Gallner began a recurring role as a devout Mormon trying to keep a polygamist's son (Douglas Smith) on the path to purity in the controversial HBO series, "Big Love" (2006- ). Meanwhile, Gallner revived his "Smallville" role in early 2007, returning as Impulse rather than The Flash - due to a feature film with the same character being developed by Warner Bros. Made acting debut in an episode of NBC's Third Watch. Made his film debut in the comedy cult film Wet Hot American Summer. Had a recurring role as superhero Bart Allen in Smallville (The WB, 2001-2006; The CW, 2006-2009).