Billy was born in Palm Beach, Florida. He has been modeling since he was little, and when he was 9 he decided he wanted to try acting. He enrolled in acting classes along with his older sister Erin Unger and younger brother Eric Unger.Billy got noticed at the 2007 Pop Con by a casting directer and later moved to L.A. He has been working there since.
He likes classic rock (like Bon Jovi, The Rolling Stones, and Aerosmith), but he also listens to newer stuff like Cold Play, an...d The Jonas Brother. His hobbies are skateboarding, surfing, and dirt biking. Billy is also a skilled martial artist, you can see some examples of this in the Opposite Day, Kickin' It, Lab Rats and the Lost Medallion. He is a fan of the Harry Potter movies, but he hasn't read any of the books. Since he is reading a script every week he does not have the time. He does not like to spend his spare time reading scripts.
Billy graduated high school in July 2011 (3 whole years early!) and will be starting college courses soon.
He started getting more noticed when his episode eith Sonny w/a chance aired. ( Sonny w/a 100% chance of meddling), and currently stars in his own Disney XD show 'Lab Rats'. He also guest starred on Disney XDs 'Kickin' it'! and A.N.T Farm on the Disney Channel.