Robert Pierrepont, 1st Earl of Kingston-upon-Hull (6 August 1584 – 25 July 1643) was an English nobleman who joined the Royalist side in the English Civil War after some delay and became lieutenant-general of the counties of Lincoln, Rutland, Huntingdon, Cambridge and Norfolk. He was killed in a friendly fire incident after being captured by Parliamentary forces.
He was the second son of Sir Henry Pierrepont of Holme Pierrepont, Nottinghamshire, and Frances Cavendish, daughter of the Rt. Hon. Sir William Cavendish and Elizabeth Hardwick. His sister became Grace, Lady Manners of Haddon Hall.
He married Gertude Talbot, daughter of Henry Talbot (1554–1596) (Henry was the son of George Talbot, 6th Earl of Shrewsbury), and Elizabeth Reyner (born 1556) on 8 Jan 1601 in Overton Longueville, Huntingdonshire.
The earl had five sons, one of whom became Henry Pierrepont, 1st Marquess of Dorchester, another was Francis Pierrepont (died 1659), a colonel in the parliamentary army and afterwards a member of the Long Parliament; and another was William Pierrepont (1608–1679), father-in-law of Gilbert Holles, 3rd Earl of Clare and also Henry Cavendish Duke of Newcastle upon Tyne. He also had a daughter, Lady Frances (born 1615) who married Philip Rolleston, Esquire. The earl was succeeded by his son, Henry.
In 1633 he bought Thoresby Park, where his son Henry built the first Thoresby Hall in 1670.