Saint Omer or St Omer most commonly refers to:

• St Omer, the common name of Saint Audomare (died c. 670)

Saint Omer may also refer to:

• Godfrey de Saint-Omer (12th century), one of the 12th century founders of the Knights Templar
• Walter of Saint Omer (d. 1174), Prince of Galilee
• Nicholas I of Saint Omer (11??-121?), French knight^{[citation needed]} who participated in the Fourth Crusade and became a lord in the Frankish Duchy of Athens, father of Bela
• Bela of Saint Omer (died 1258), Lord of one half of Thebes, father of Nicholas II, Otho and John
• Nicholas II of Saint Omer (died 1294), Lord of one half of Thebes
• Otho of Saint Omer (died 1299), Lord of one half of Thebes
• John of Saint Omer (13th century), Marshal of Achaea, father of Nicholas III
• Nicholas III of Saint Omer (died 1314), Lord of one half of Thebes and Marshal of Achaea

• Saint-Omer, Quebec, a town in L'Islet Regional County Municipality
• Saint-Omer, Gaspésie–Îles-de-la-Madeleine, Quebec

• Saint-Omer, Calvados
• Saint-Omer-en-Chaussée, Oise
• Saint-Omer, Pas-de-Calais

• St. Omer, a small village in the municipality of Suhlendorf, Germany

• Saint Omer, Indiana

• Saint Omer (film), 2022 film by Alice Diop
• Sant Omer, a similarly named composer of Trecento music
• College of St. Omer, a Catholic school that operated from about 1594 to 1793
• Battle of Saint-Omer, Hundred Years War, 1340
• Hours of Saint-Omer, illuminated manuscript of c. 1320
• Siege of Saint-Omer, Thirty Years War, 1638