Humphrey Cornewall (1616–1688) was an English member of parliament.
He was born in 1616, the eldest son of John Cornewall and Mary Barneby, and was baptised at Eye, Herefordshire on 14 July 1616.
During the English Civil War, he served on the Royalist side under Sir Henry Lingen, though he later claimed to have done so only to defend himself and his neighbours from the depredations of cavalier soldiers. Edward Harley attested that Cornewall was forced to participate in an assault on Stokesay Castle and to sit on a royalist grand jury. For this support of the cause of King Charles, he was fined £222 (equivalent to £28,459 in 2015) by the victorious Parliamentarians on 1 July 1647. Successfully pleading poverty, he only actually paid £21 16s of this amount. He was also suspected of complicity with George Booth's rising in 1659.
The Restoration brought about a marked improvement in Cornewall's fortunes. His name was put forward as a potential Knight of the Royal Oak. He served as a Justice of the peace in Herefordshire from 1660 until his death, and commissioner for assessment in that county from 1660 to 1680. He was elected to represent Leominster in the Cavalier Parliament of 1661. He was a Major in the Herefordshire Militia by 1662, in which year he also became Deputy Lieutenant of Herefordshire and a commissioner for loyal and indigent officers. In 1670 he became a member of the Council in the Marches of Wales. He was made a Captain in the Admiralty Regiment in 1672, and a commissioner for recusants in 1675. After leaving parliament in 1679, he concentrated his attention on Ludlow, where he had been a freeman since 1676. He was an Alderman from 1685 onwards, and was Mayor from 1686 to 1687.