Emma of Altdorf, also known as Hemma (German: Emma von Altdorf; c. 803/808 – 31 January 876) was a Frankish noblewoman, a member of the Elder House of Welf and as the wife of Louis the German Queen consort of Eastern Francia.
Her father was Welf, Count of Altorf; her mother was Heilwig of Saxony (born c.775, died after 833), the daughter of Count Isanbart. Her sister was Judith (sometimes called of Bavaria), who was the second wife of Emperor Louis the Pious, and by marriage Queen and Empress of the Franks.
In 827 at Regensburg, Emma married Louis the German, son of the Carolingian Emperor Louis, and stepson of Emma's sister. She was thus from 817–843 Queen consort of Bavaria. She was given in 833, by her husband Louis, Obermünster Abbey in Regensburg.
She is described as having had great qualities: an uncommon courage and talent, deployed on more than one occasion. In particular, she led an army against Adelchis of Benevento, when he revolted against Louis the German; it is said that, frightened by the arrival of the Queen, the traitor fled by boat to seek safety in Corsica. The Annals of Saint-Bertin however reproach Emma for a pride which displeased the people of Italy.
By Louis, she had eight children:
- Hildegard (827–856)
- Carloman (828–880)
- Ermengard ( c. 830-866)
- Gisela, married to Berctolf, Count of Swabia. Grandmother of Cunigunde of Swabia, wife of Conrad I.
- Louis the Younger (830–882)
- Bertha (died 877)
- Charles the Fat (839–888)
Her sons became Kings; three of her daughters became nuns.