Billy and his brother Tommy Maximoff were the twin children of Wanda Maximoff, born inside the Westview anomaly. Their existence was highly unnatural, as Wanda's pregnancy progressed from early signs to full birth in less than a full day. Furthermore, during the very next day both twins aged rapidly first from toddlers to 5-year olds and later that same morning into 10-year olds, with appropriate intelligence, speech and personalities. It was soon discovered that the twins possessed supernatural powers similar to those of their mother and her brother, with Billy remotely feeling the distress of his father telepathically.
When their entire existence was shown to be tied to the anomaly, Wanda nevertheless decided to let down the barrier, dissolving the reality changes that it manifested. She and Vision went back to their home with the kids, where after tucking them in bed she tearfully said goodnight to Billy and Tommy shortly before the anomaly receded entirely.
- Telepathy: Can hear people's thoughts and feel their presence across a city-wide range.
- Hypnosis: Manipulated the military to stop moving so his brother could desarm them.
- Superhuman Reflexes: Billy was able to stop an incoming bullet with his telekinesis.
- Billy was portrayed by Baylen Bielitz as a 5-year old and Julian Hilliard as a 10-year old in the Disney+ mini-series WandaVision.
- Jackson Robert Scott was Hilliard's stand-in/reference.
- 7 appearance(s) of William Maximoff (Earth-199999)
- 1 mention(s) of William Maximoff (Earth-199999)
- 7 image(s) of William Maximoff (Earth-199999)
- 1 quotation(s) by or about William Maximoff (Earth-199999)