William Douglas, 10th earl (c. 1554-1611), was the son of William, the 9th earl (1533-1591). He studied at St. Andrews University and joined the household of the earl of Morton. Subsequently, while visiting the French court, he became a Roman Catholic, and was in consequence, on his return, disinherited and placed under restraint. Nevertheless he succeeded to his father's titles and estates in 1591, and though in 1592 he was disgraced for his complicity in Lord Bothwell's plot, he was soon liberated and performed useful services as the king's lieutenant in the north of Scotland. In July 1592, however, he was asking for help from Elizabeth in a plot with Erroll and other lords against Sir John Maitland, the chancellor, and protesting his absolute rejection of Spanish offers, while in October he signed the Spanish Blanks (see ERROLL, FRANCIS HAY, 9th EARL OF) and was imprisoned (on the discovery of the treason) in Edinburgh Castle on his return in January 1593. He succeeded on the 13th in escaping by the help of his countess, joining the earls of Huntly and Erroll in the north.
They were offered an act of "oblivion" or "abolition" provided they renounced their religion or quitted Scotland. Declining these conditions they were declared traitors and "forfeited." They remained in rebellion, and in July 1594 an attack made by them on Aberdeen roused James's anger. Huntly and Erroll were subdued by James himself in the north, and Angus failed in an attempt upon Edinburgh in concert with the earl of Bothwell. Subsequently in 1597 they all renounced their religion, declared themselves Presbyterians, and were restored to their estates and honours. Angus was again included in the privy council, and in June 1598 was appointed the king's lieutenant in southern Scotland, in which capacity he showed great zeal and conducted the "Raid of Dumfries," as the campaign against the Johnstones was called. Not long afterwards, Angus, offended at the advancement of Huntly to a marquisate, recanted, resisted all the arguments of the ministers to bring him to a "better mind," and was again excommunicated in 1608. In 1609 he withdrew to France, and died in Paris on the 3rd of March 1611. He was succeeded by his son William, as 11th earl of Angus, afterwards 1st marquis of Douglas (1580-1660). The title is now held by the dukes of Hamilton.
The Douglas Book, by Sir W. Fraser (1885); History of the House of Douglas and Angus, by D. Hume of Godscroft (1748, legendary in some respects); History of the House of Douglas, by Sir H. Maxwell (1902).
 Lindsay of Pitscottie (1814), ii. 314.