King Gregor is the benevolent ruler of the fictional english kingdom of Dunwyn. He is concerned greatly about the problems of his people and protects them against villains and criminals such as his archenemy Duke Igthorn. His most prized possession is none other than his own daughter, Princess Calla, whom he would give up his kingdom and life for in order to keep her safe.
Like many human characters in the series, he is unaware that the mythological Gummi Bears live in Dunwyn, believeing that they are merely just a fairytale. Throughout the series, he retains this belief, but he has met them unknowingly on several occasions (usually while they were in disguise).
It is revealed sometime before the show's timeline that his archenemy Duke Igthorn was once a knight under his court. However Igthorn had betrayed him and attempted to overthrow him from the court but ultimately failed to, resulting in him being exiled from the kingdom. Since then, Igthorn has tried countless times to capture him and Dunwyn by means of using a super weapon against his kingdom or kidnapping his daughter. Often times this would either ultimately fail or initially succeed but soon be foiled by the Gummi Bears and Cavin.
In the two-part series finale "King Igthorn", King Gregor is finally defeated by Duke Igthorn, who then takes his crown, and imprisons him, his daughter, and his court of knights. King Gregor is soon however freed after Cavin and the Gummis lead a sneak attack on Igthorn. Gregor soon joins the battle after his knights are freed in an attempt to drive off Igthorn permanently and is last seen driving off Igthorn's army of ogres.