Levett was born in Ashwell, Rutland, to an Anglo-Norman family with roots in Sussex going back to the Norman Conquest.
Richard Levett, born in Melton Mowbray, Leicestershire, and a graduate of Magdalen Hall, Oxford, was the intruding rector at Ashwell from 1646 until 1660.
[7] William Levett had at least two brothers, Richard, who became Lord Mayor of London, and Francis, an international trader; these two were in business together.
[17] In his will Levett directed his body be decently interred, "without any manner of speech, or funerall oration, or either good or bad verses, and without any opening of it, or the least dissection of it whatever" in the Cathedral at Christ Church.
When word of Dean Levett's death reached Oxford on 11 February 1694, a Sunday morning, bells were rung in honour of the late Principal.