Alexander III (Scottish Gaelic: Alaxandair mac Alaxandair; Modern Gaelic: Alasdair mac Alasdair; 4 September 1241 – 19 March 1286) was King of Alba (Scotland) from 6 July 1249 until his death. He concluded the Treaty of Perth, by which Scotland acquired sovereignty over the Western Isles and the Isle of Man. His heir and only grandchild, Margaret, Maid of Norway, died before she could be crowned.