Bela of Saint Omer was aFrench knight, descended from aFauquembergues family who werecastellans of the eponymous castle ofSaint-Omer.^[1]

His father,Nicholas I of Saint Omer, received lands inBoeotia in the aftermath of theFourth Crusade.^[2] He later marriedMargaret of Hungary, the widow ofBoniface of Montferrat,Lord of Thessalonica (died 1207).^[3] It is unclear when the marriage took place: some accounts mention that Nicholas died already in 1212^[2] (probably by a misreading of the genealogical table published byKarl Hopf inChroniques gréco-romanes inédites ou peu connues) but F. Van Tricht dates the marriage to after 1217^[4] and J. Longnon "not before 1223".^[5]

Bela, who was named after his maternal grandfather,Béla III of Hungary, was the eldest son of the couple, and was followed by his brotherWilliam.^[2][4] In 1240, Bela married the sister of theLord of Athens and Thebes,Guy I de la Roche. As part of herdowry, he received one half ofThebes as his domain.^[2][1] They had three sons,Nicholas II of Saint Omer (d. 1294), who succeeded in Thebes,Otho of Saint Omer (d. before 1299), andJohn of Saint Omer (d. 1311), who became Marshal of thePrincipality of Achaea.^[2][3]

• Bon, Antoine (1969).La Morée franque. Recherches historiques, topographiques et archéologiques sur la principauté d'Achaïe [The Frankish Morea. Historical, Topographic and Archaeological Studies on the Principality of Achaea] (in French). Paris: De Boccard.OCLC 869621129.
• Longnon, Jean (1969) [1962]."The Frankish States in Greece, 1204–1311". InSetton, Kenneth M.;Wolff, Robert Lee; Hazard, Harry W. (eds.).A History of the Crusades, Volume II: The Later Crusades, 1189–1311 (Second ed.). Madison, Milwaukee, and London: University of Wisconsin Press. pp. 234–275.ISBN 0-299-04844-6.
• Perra, Foteini (2011).Οικογένεια Σεντ Ομέρ.Encyclopedia of the Hellenic World, Boeotia (in Greek). Foundation of the Hellenic World.
• Van Tricht, Filip (2011).The LatinRenovatio of Byzantium: The Empire of Constantinople (1204–1228). Leiden: Brill.ISBN 978-90-04-20323-5.

• 13th-century French nobility
• People from the Duchy of Athens
• Medieval Thebes
• Christians of the Crusades
• Saint-Omer family
• Jure uxoris lords

• CS1 French-language sources (fr)
• CS1 uses Greek-language script (el)
• CS1 Greek-language sources (el)
• Year of death missing
• Year of birth unknown