Colonel Sir Gilbert Gerard (died January 1646) was a Royalist officer during the English Civil War.
Gilbert and Ratcliffe were twin sons of Ratcliffe Gerard, and Elizabeth, daughter and heir of Sir Charles Somerset.
Gerard was the colonel of a Royalist regiment of foot (his twin brother, Ratcliffel,was his lieutenant-colonel) that was already in the field before the first major pitched battle took place. Gerard's Regiment joined two other Lancashire Royalist regiments under the command of Sir Charles Gerard's (his nephew) and Lord Molyneux in besieged Manchester, but the failed to take the city before they left for the general rendezvous with the Royalist army which was assembling in Shropshire before advancing towards London. The advancing Royalist army fought the Parliamentary army at Edgehill (23 October 1642) in an indecisive engagement. Gerard's regiment fought in the front line along with Molyneux and a Welsh regiment of Sir Thomas Salusbury, and although indecisive the battle for those in the font line came to a push of pikes.
After the advance on London and the Battle of Brentford, Gerard marched with his regiment and that of Molyneux to Brill to take up his appointment of Governor of Brill and to oversee its fortification and to defend the place against incursions by Parliamentary forces. It was one of several satellite locations chosen to protect Oxford and the Kings court, and so Gerard oversaw the building of earthworks to turn the area near the Church into a fort. While Molyneux was absent Gerard with the aid of a regiment of horse (cavalry) commanded by Colonel Charles Gerard, beat of a strong attack by Colonel Arthur Goodwin on 27 January 1643.
For the summer campaign of 1643 Gerard and his regiment were assigned to the Royalist forces in the south west. They were involved in the siege and storming of Bristol (26 July 1643) and were in the front-line at the First Battle of Newbury on 20 September 1643. In December Gerard took up an appointment as Governor of Worcester and his regiment garrisoned the town.