William Downham (1511–1577) was bishop of Chester.
Under Mary of England, he was chaplain to her sister Princess Elizabeth. He became bishop of Chester in 1561, shortly after Elizabeth's accession.
As bishop, he was considered rather ineffectual against the Roman Catholics, preferring not to offend the gentry. The reformer Christopher Goodman attacked him in 1571, as supine, on a pretext of the continuing Whitsun plays.
He had further problems with the diocesan finances, being dependent on rents that could prove hard to collect. He also had very few university graduates among his candidates for ordination.
George Downame and John Downame were his sons.