Colonel Francis Hacker (died 19 October 1660) was an English soldier who fought for Parliament during the English Civil War and one of the Regicides of King Charles I of England.
Hacker was third son of Francis Hacker of East Bridgford and Colston Basset, Nottinghamshire, by Margaret, daughter of Walter Whalley of Cotgrave. From the outbreak of the English Civil War Hacker vehemently supported the Parliamentary cause, though the rest of his family seem to have been royalists. On 10 July 1644 he was appointed one of the militia committee for the county of Leicester, the scene of most of his exploits during the Civil War, On 27 November 1643 he and several others of the Leicestershire committee were surprised and taken prisoners at Melton Mowbray by Gervase Lucas, the Royalist governor of Belvoir Castle. A month later Parliament ordered that he should be exchanged for Colonel Sands.
At the capture of Leicester by the king in May 1645 Hacker, who distinguished himself in the defence, was again taken prisoner. Hacker was nevertheless attacked for his conduct during the defence, but he was warmly defended in a pamphlet published by the Leicester committee. His services are there enumerated at length, and special commendation is bestowed on his conduct at the taking of Bagworth House and his defeat of the enemy at Belvoir, where he was in command of the Leicester, Nottingham, and Derby horse (cavalry). Hacker is further credited with having freely given "all the prizes that ever he took" to the state and to his soldiers, and with having, while prisoner at Belvoir, refused with scorn an offer of "pardon and the command of a regiment of horse to change his side". "At the king's taking of Leicester", the pamphleteer proceeds, he "was so much prized by the enemy as they offered him the command of a choice regiment of horse to serve the king". At the defeat of the Royalists at the Battle of Willoughby Field in Nottinghamshire (5 July 1648) Hacker commanded the left wing of the Parliamentary forces.
During the trial of Charles I, Hacker was one of the officers specially charged with the custody of the King, and usually commanded the guard of halberdiers which escorted Charles to and from Westminster Hall. He was one of the three officers to whom the warrant for the King's execution was addressed, was present himself on the scaffold, supervised the execution, and signed the order to the executioner. According to Herbert he treated the King respectfully.