Sir William Brereton, 1st Baronet, English commander and politician (b. 1604)
Sir William Brereton, 1st Baronet, (1604–1661), was an English Puritan who owned extensive estates in Cheshire, and Member of Parliament for Cheshire county at various times between 1628 and 1653. During the First English Civil War, he was commander of Parliamentarian forces in the North Midlands.

In the 1630s, he travelled extensively through France, the Dutch Republic, Scotland, and Ireland; his travel journals from 1634 and 1635 were published in the 19th century. His records and letters from the Civil War are a primary source for Parliamentary local administration in the period, as well as the internal divisions that led to the Second English Civil War.

Despite lacking prior military experience, he proved an energetic and capable soldier, and was one of the most powerful men in England when the First Civil War ended in 1646. However, he gave up his local offices, and although nominated as a judge, refused to attend the trial of Charles I in January 1649. He was elected to the Council of State in 1652 and 1653 but rarely attended, living in semi-retirement in London.

He resumed his seat for Cheshire when the Long Parliament was reinstated in 1659, until its dissolution in March 1660, and died on 7 April 1661.