William Byrd (; birth date variously given as c.1539/40 or 1543 – 4 July 1623) was an English composer of the Renaissance. Widely considered to be one of the greatest composers of the Renaissance and one of the greatest British composers, he had a huge influence on composers both from his native England and those on the continent. He wrote in many of the forms current in England at the time, including various types of sacred and secular polyphony, keyboard (the so-called Virginalist school), and consort music. Although he produced sacred music for Anglican services, sometime during the 1570s he became a Roman Catholic and wrote Catholic sacred music later in his life.