He married Avicia de Lancaster (1088 – c. 1150) in La Marche, Normandy, France. She was possibly the daughter of William de Lancaster I and Countess Gundred de Warenne, daughter of William de Warenne, 2nd Earl of Surrey. In 1114, she bore a daughter, Margaret Peverel. Another member of his family, Maude Peverel (a sister or daughter) was, by 1120, the first wife of Robert fitz Martin.
William inherited the Honour of Peverel.
King Henry II dispossessed William of the Honour in 1153, for conspiring to poison Ranulf de Gernon, although historians speculate that the King wished to punish him for his "wickedness and treason" in supporting King Stephen. The Earl died before he took possession of the Honour, and it stayed in the Crown for about a half century.
- Hart, Jr., Albert Douglass. "William Peverel". ourfolkgen.com. Archived from the original on 1 July 2020. Retrieved 1 July 2020.
- Cokayne, George E.; other authors (1887–98). The Complete Peerage (extant, extinct or dormant). Vol. 4 (4th ed.). pp. 762–768.
- "Langar Hall: a microcosm of English history". Baronage. Archived from the original on 13 May 2008. Retrieved 13 May 2008.