John Sherlock (c.1705 - 25 July 1794) was an Irish-born brigadier general in the Ultonia Regiment in Spain. He successfully defended Melilla during a 100-day siege by Moroccan troops. John was the son of Peter Sherlock, who had been made a baronet and knight by titular king, James III, the Old Pretender, in 1716. However, during the Irish Rebellion of 1641, the Sherlock family lost its extensive land holdings in County Waterford. Like many Catholic Irish, John emigrated to Spain with hopes of returning to Ireland once a Catholic was king of England again. And like his father and grandfather he served in the Ultonia Regiment (i.e. Ulster Regiment), part of the Irish Brigade of the Spanish Army.