He is the son of Wanda Maximoff and Vision, and younger twin brother of Tommy Maximoff. He was conceived through the effects of Wanda's chaos magic, which also granted him psionic powers, similar to his mother. Billy was born in Westview, following his mother's accelerated pregnancy, and further aged himself up. As each episode passed, he adapted into a new time period, staring from the 1970s, to the present
After Wanda removed the Hex that barricaded the town, Billy's soul was reincarnated into that of William Kaplan, a thirteen year old, who died from a car crash in Eastview, concurrently as the hex began to fade. Inhibiting this new body, Billy assumed the deceased teen's identity, living as William Kaplan, and would go on to develop an interest in the craft, while questioning his identity. He would later track Agatha Harkness, with whom he formed a coven, to walk down the legendary Witches' Road, in hopes of finding his brother, Tommy. Billy reincarnates his brother's soul into the body of a dying teenager and battles Lady Death, volunteering to go with her until Agatha sacrifices herself for Billy. Billy returns home before realizing he created the road with his mind and joins ghost Agatha to venture on a journey to find Tommy
Billy Maximoff first appears in the third episode of WandaVision and was portrayed by Baylen Bielitz and Julian Hilliard. His reincarnated form first appears in the very first episode of Agatha All Along, and is portrayed by Joe Locke
Billy Maximoff, was created by Steve Englehart and Richard Howell. His reincarnated form, Wiccan, was created by Allan Heinberg and Jim Cheung
