Alfonso IV (Alfonso the Kind) (b. 1299, Barcelona, d. 1336, Barcelona), king of Aragon from 1327 to 1336, son of James II. He was well-intentioned but weak. His reign was marked by a serious revolt in Sardinia, which led to war with Genoa, and by the establishment of diplomatic relations with the Moorish kingdoms of North Africa. The failure of the king to resist the efforts of his second wife to further the future of her sons at the expense of Alfonso's heir, Peter, led to serious political disturbances.