English composer of polyphonic sacred music and father of the organist and composer John Mundy (Mundy, John).

Little is known of William Mundy's early life other than that he was the son of Thomas Mundy, a sexton at St. Mary-at-Hill in London. William Mundy was head chorister of Westminster Abbey in 1543, later became lay vicar choral of St. Paul's Cathedral in London, and from 1564 was a gentleman of the Chapel Royal. There is some uncertainty about which Mundy, William or John, composed the works for which authorship is not clearly specified. Much of William's known surviving music is set to Latin texts, including 2 masses and more than 20 motets (motet) written in the broad polyphonic style of English music that preceded the madrigal. He also wrote a number of complex and ornate votive antiphons (works in honour of the Virgin Mary or a particular saint), such as "Vox Patris caelestis" (“The Voice of the Heavenly Father”). His surviving English church music includes two services and six anthems; "O Lord, the Maker of All Things" (1641) and "O Lord, I Bow the Knees" (1641) are well-known examples of post-Reformation church music.