Adalgisel or Adalgis (Adalgyselus ducis in contemporary Latin) was a Frankish duke and the mayor of the palace of Austrasia.
Along with Cunibert, Bishop of Cologne, he acted as regent for the young king.
Adalgisel, Cunibert, and Sigebert were all appointed by Dagobert I. Adalgisel and Grimoald led the Austrasian army against the Thuringii sometime around 639, but their magnates defected and they were forced to concentrate on protecting the young king's life.
Not long after, he ceased to be duke and was replaced by Pepin of Landen, probably following the nearly concurrent death of Dagobert.
He left a son Bobo, who had accompanied him into battle against the Thuringii, and was later Duke of Auvergne.