William Knollys, 1st Earl of Banbury (1544[1] – 25 May 1632) was an English nobleman at the court of Queen Elizabeth I and King James I.

[2] He was the son of Sir Francis Knollys, of Greys Court in Oxfordshire, and of Reading, in Berkshire, and his wife, Catherine Carey.

William inherited both Greys Court and the rebuilt Caversham Park mansion on the death of his father in 1596.

Intended to be her protector from wayward influence of courtiers, he fell in love with her himself and wished his wife dead so he could marry her.

As a result, the House of Lords refused to seat them as Earls of Banbury and considered them to be illegitimate sons of Elizabeth and Edward Vaux.