Sir William Brownlow, 1st Baronet (c. 1595–1666)^[1] of Humby in Lincolnshire, was an English politician and barrister.

He was the second son of Richard Brownlow (1553–1638) of Belton in Lincolnshire, which manor he purchased, Chief Prothonotary of the Court of Common Pleas, by his wife Katharine Page, a daughter of John Page^[2] of Wembley in Middlesex. His elder brother was Sir John Brownlow, 1st Baronet (c.1594-1679) of Belton,^[2] who was created a baronet "of Belton" one day before himself.

He was educated at St Mary Hall, Oxford, where he graduated with a Bachelor of Arts in 1610 or 1611.^{[citation needed]} In 1617 Brownlow was called to the bar by the Inner Temple.^{[citation needed]} Despite having been created by King Charles I a baronet, "of Humby, in the County of Lincoln", on 27 June 1641,^[3] one day after the baronetcy of his elder brother, he became a Parliamentarian during the Civil War.^{[citation needed]} From 1653 he sat in the Long Parliament for Lincolnshire.^{[citation needed]}

In about 1624 he married Elizabeth Duncombe, daughter of William Duncombe, and had by her a daughter and a son:

• Sir Richard Brownlow, 2nd Baronet (d.1668) of Humby, who succeeded to the baronetcy.^{[citation needed]}