Krugarr is a Lem, a race of extremely long-lived red-skin aliens. He was once a member of the Mourners, acting as their 'Listener.' During the 22nd century Doctor Strange, who survived the Martian Master invasion by removing himself from the planet and had use his magic to expand his lifetime like his master. Strange found Krugarr on Lem, who agreed to become his apprentice and learn the ways of magic.
Krugarr succeeded Strange as Sorcerer Supreme, with Strange now calling himself the Ancient One like his own master was previously. Krugarr battled Strange's ancient foe Dormammu.
Krugarr accepted the Inhuman Talon as his apprentice for a while until Talon was rejected after becoming more feral. However, the two seemed to reconcile and Talon resumed his studies on Lem.