Nicholas I of Saint Omer

Nicholas I of Saint Omer was a French knight 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 in northern France, and Ida of Avesnes. 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. He was rewarded with possessions in Euboea, but was dead by August 1205. Nicholas remained in his native region until ca. 1208, after which he and his brother James came to Greece, where they received a fief at the site of ancient Thespiae, west of Thebes. According to F. Van Tricht, the fief may have formed part of the Templar possessions that were confiscated ca. 1209 by the Latin Emperor Henry of Flanders.

Nicholas later married Margaret of Hungary, the widow of Boniface of Montferrat, who died in 1207. It is unclear when the marriage took place: traditional accounts mention that Nicholas died already in 1212 or 1214, but F. Van Tricht dates the marriage to after 1217.

With Margaret he had two sons, William and Bela. The latter would marry the sister of Guy I de la Roche, 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.