Nicholas I of Saint Omer was a French knight[citation needed] who in the aftermath of the Fourth Crusade became a lord in the Frankish Duchy of Athens.
Nicholas was a younger son of William IV of Saint Omer, castellan of Saint-Omer then in Flanders, and Ida of Avesnes.
[1][2] Ida's brother James of Avesnes took part in the Fourth Crusade (1203–04) and accompanied Boniface of Montferrat in the conquest and partition of Greece in its aftermath.
1208, after which he and his brother James came to Greece, where they received a fief at Erimokastro, the site of ancient Thespiae, west of Thebes.
Bela would marry Bonne de La Roche, the sister of Guy I, the Duke of Athens, become lord of one half of Thebes, and lay the foundations for the rise of the Saint Omer family to a prominent position in Frankish Greece.