Gandalf Alfgeirsson (Old Norse: Gandálf Álfgeirsson) was king of the petty kingdom Vingulmark, now part of Norway.

His three sons, Hysing, Helsing, and Hake, attempted to ambush Halfdan the Black at night but he escaped into the forest. After raising an army, he returned and defeated the brothers, killing Hysing and Helsing. Hake fled from the country and Halfdan became king of all of Vingulmark.