Robert Maxwell, 1st Earl of Nithsdale, was a Scottish nobleman. He succeeded his brother as 10th Lord Maxwell in 1613, and was created Earl of Nithsdale in 1620. General of Scots in Danish-Norwegian service during the Thirty Years' War. A loyal supporter of Charles I and a prominent Catholic, he lost his titles and estates in 1645, dying on the Isle of Man in 1646.

There was a complicated involvement between Scotland and the Thirty Years' War of 1618–1648. Scotland and the Scots were heavily entangled in both the diplomatic and military events which centred on the Holy Roman Empire. There were a number of reasons for this participation.