Arthgal ap Dyfnwal (died 872) was a ninth-century king of Alt Clut. He descended from a long line of rulers of the British Kingdom of Alt Clut. Either he or his father, Dyfnwal ap Rhydderch, King of Alt Clut, may have reigned when the Britons are recorded to have burned the Pictish ecclesiastical site of Dunblane in 849.