Bill Johnson was born in Jacksonville, Florida to his Australian parents Katherine and Aiden Johnson and has an older sister Courtney (who is 8 years older than him). When he was 3 years old, he and his family moved to Malibu, California. He and one of the main two tritagonists Tran Wu have been good friends ever since Bill was 11 and Tran was 7 just a week before Bill's 12th birthday. At the age of 13 in the Jeet Kune Do match, he and his family and other friends sat in the audience and saw him fight the school bullies Jack Byron, Shredder, Macy Rutherford, Sam "Schrader" Hader, Sara Perry and Chip Winslow, knock them down and win a prize Chinese scab necklace from his aunt after that.
Bill became an uncle at the age of 20 with the birth of his niece Alexis and again at the age of 27 with the birth of his nephew Jared (who is also Alexis's younger brother).
- His favorite video game is the Mortal Kombat franchise.