William Byrd was an English composer of the Elizabethan era. He is considered one of the most important composers of the period and is best known for his vocal music, particularly his sacred works. He wrote a large number of motets, anthems, and other sacred music, as well as instrumental pieces. He was also a prolific writer of madrigals and other secular vocal music. His works are still performed today and he is remembered as one of the greatest composers of the Elizabethan era.