| John of Saint Omer | |
| Succession: | Lord of a third of the Barony of Akova, Marshal of the Principality of Achaea |
| Reign: | 1276–unknown |
| Successor: | Nicholas III of Saint Omer |
| Spouse: | Margaret of Passavant |
| Father: | Bela of Saint Omer |
| Mother: | Bonne de la Roche |
| Issue: | Nicholas III of Saint Omer |
| Religion: | Roman Catholic |
John of Saint Omer (Jean de Saint-Omer) was baron of a third of Akova and marshal of the Principality of Achaea.
He was a younger son of Bela of Saint Omer and Bonne de la Roche, sister of the Lord of Athens and Thebes, Guy I de la Roche. Upon their marriage, in 1240, Guy gave Bela the lordship over half of Thebes.[1] [2] John participated, along with his brothers Nicholas II and Otho, in the War of the Euboeote Succession in the ranks of the coalition of most of the princes of Frankish Greece, who opposed the expansionist policies of the Prince of Achaea, William II of Villehardouin.[2] [3]
John married Margaret of Passavant in 1276, but was unsuccessful in securing her inheritance of the Barony of Akova in the Principality of Achaea, which had been appropriated by the Prince after the death of baron Walter of Rosières. Despite the support of his brother Nicholas, he managed to receive only a third of the barony (eight fiefs), as well as the post of hereditary marshal of the Principality.[2] [4]
From his marriage he had one son, Nicholas III of Saint Omer.[2] [5]