Ermengarde, or Irmengarde de Hesbaye (c.778-818) was the daughter of Ingerman, Count of Hesbania (Hesbaye, now in Liège, Belgium) and Hedwig of Bavaria.

Her paternal grandfather Gunderland, Count of Hesbania was himself a son of Sigrand, Count of Hesbania and Landrade of Austrasia. Landrade was reportedly daughter of Charles Martel by either Chrotrud or Swanachild.

Ermengarde married in 794/795 Louis the Pious, king of Aquitania, king of Franks, king of Italy, ruler of the Holy Roman Empire.

She had six children :
• Lothair I, born 795 in Altdorf, Bavaria
• Pepin of Aquitaine, born 797
• Adelaide, born. ca. 799. Possible wife of Robert the Strong, possible mother of Odo, Count of Paris and Robert I of France.
• Rotrude, born 800.
• Hildegard / Matilda, born ca. 802. Wife of Gerard, Count of Auvergne, possible mother of Ranulf I of Poitiers.
• Louis the German, born ca. 805.
She died at Angers, France on 3 October 818. Louis was married to Judith a few years later and became father of Charles the Bald.