Donald III of Scotland was the son of Duncan I. He was born around 1033CE and became Mormaer of Gowry, around 1060. On the death of his uncle, Malcolm III Canmore, in 1093, Donald took the Scots throne, in joint rule with his nephew, Edmund. The next year, supported by Anglo-Normans, Duncan II, Malcom's son, seized the throne, and deposed Donald and Edmund. He lived until November 1094CE, when he died in battle, and Donald and Edmund retook the throne. Donald ruled over the northern parts of Scotland, Edmund over the southern. In 1097 they were again deposed, in this instance in favour of another of Malcolm's sons Edgar (who appears to have had help from the English William Rufus). Donald was imprisoned, and died in 1099. (Edmund, of whom no more is known, is supposed to have escaped death and to have become a monk.)
At some point he married and had a daughter, Bethoc. She married an Anglo-Saxon lord, in Northumbria, Ughtred of Tynedale, and from this marriage came, at length, the candidiature of the Comyn family for the throne of Scotland.
Donald was also known as Donald Bane or Donalbane, by which name he appears in Shakespeare's Macbeth)