As of now, Billy’s father is unidentified — intentionally left as an unanswered question to drive Billy’s character arc of seeking belonging and identity outside of bloodlines.
Here’s a solid write-up on the subject: who is billy's father in wizards beyond waverly place
Through context and subtle clues, it is strongly implied — and later confirmed via casting and character interactions — that , possibly one who is absent, deceased, or unable to care for him. The show uses Billy’s mysterious origins as a plot device to explore themes of found family and mentorship. As of now, Billy’s father is unidentified —
That said, a key reveal in the series points to , leaving Billy to be raised by others in the wizard community. No canonical connection to the original Wizards of Waverly Place main family (the Russos) exists — Billy is not related to Alex, Justin, or Max. That said, a key reveal in the series