Geoffrey of Sergines (c. 1205 - 1269) was a French crusader who served as seneschal of the Kingdom of Jerusalem from 1254 until 1269.
Geoffrey was born around 1205, a native of Sergines, a village north of Sens and close to Paris. His family held high offices in the Church: a brother was abbot of Saint-Jacques de Provins; an uncle, Peter of Sergines, became archbishop of Tyre; and Margaret of Sergines, abbess of Montivilliers, may have also been a relative.
Geoffrey became close to King Louis IX of France; in 1236, he received a permission from his liege-lord, Count Hugh of Blois, to become the king's liegeman instead. Geoffrey probably arrived in Palestine on 1 September 1239 with the Barons' Crusade, led by King Theobald I of Navarre and Duke Hugh IV of Burgundy. He returned to France five years later. In 1248, he set out on the Seventh Crusade with Louis. During Louis's rule in Damietta, Geoffrey sat on the king's council and was one of eight select companions who stood guard over the king. After their defeat at the battle of Mansurah in 1250, Geoffrey alone ensured Louis's safe retreat. Louis left for France in April 1254. He left Geoffrey behind as the seneschal of the Kingdom of Jerusalem and commander of a special French contingent.
As seneschal, Geoffrey became one of the political leaders of the dwindling kingdom, which was then centered on Acre. From 1259 until September 1261 and again from 1264 to 1267, he ruled it on behalf of absent regents. He gained a reputation as an impartial but severe justiciar. When a knight killed the bishop of Famagusta, Stephen of Mezel, and took refuge in Acre's Pisan quarter, Geoffrey invaded and forced the powerful Italian merchants to hand over the murderer.
In the early 1260s, Geoffrey traveled back to Europe, where he again took the cross and prepared to return to Palestine with a large force. In addition to commanding the French king's troops, he formed his own company. His dedication to the crusading movement almost bankrupted him; in 1263, Pope Urban IV asked the kings of France and Navarre to assist him with the proceeds of a market tax. Urban's successor, Clement IV, also recognized Geoffrey's value to the crusader kingdom. Geoffrey's financial difficulties continued, however. In 1267, he considered leaving Palestine to sell his fiefs in France. He died on 11 April 1269.