Matthew Stewart, 4th Earl of Lennox^[1] (21 September 1516 – 4 September 1571), was the fourth Earl of Lennox, and a leader of the Catholic nobility in Scotland. He was the son of John Stewart, 3rd Earl of Lennox and Lady Elizabeth Stewart, daughter of John Stewart, 1st Earl of Atholl. His grandson was King James VI of Scotland and I of England.

Matthew Stewart succeeded as Earl of Lennox upon the death of his father on 4 September 1526. His mother sent Matthew and his younger brother John to France to the care of their kinsman Robert Stewart, 4th Lord of Aubigny, who enrolled them in the Garde Écossaise.^[2]

When James V of Scotland died in 1542, Cardinal Beaton urged Matthew Stewart to return to Scotland to rival James Hamilton, the Earl of Arran. Lennox arrived at Dumbarton Castle, his stronghold, with two ships in March, just days after Parliament had declared Arran as Regent and heir to the throne after the infant Queen Mary of Scots. Both Arran and Lennox had claims to the throne as descendants of Mary Stewart, daughter of King James II of Scotland, but Arran had the better claim as a grandson through a male line, while Lennox was a great-grandson through a female line. Lennox however claimed that Arran was illegitimate because his father had failed to divorce his first wife before marrying Arran's mother.^[3]

Arran made the Treaty of Greenwich with England on 1 July 1543, that betrothed Mary to Prince Edward Tudor, the son and heir of King Henry VIII of England. Regent Arran began to fortify Linlithgow Palace, where Mary was held with her mother, Mary of Guise, the Dowager Queen of Scotland. Lennox allied with the pro-French Cardinal Beaton, and their forces camped outside the palace, but lacked artillery for an assault. Their representatives parleyed with Arran's men at Kirkliston, near Edinburgh, and agreed that Arran would rule with the advice of a council, and Mary would be moved to Stirling Castle. Lennox escorted Mary to Stirling on 26 July 1543.^[4]

Although Lennox had come to Scotland lured by the prospect of marriage to the widow Mary of Guise, by September, Lennox had been offered the chance to marry Lady Margaret Douglas, daughter of the Dowager Queen Margaret Tudor (wife of King James IV of Scotland and sister of King Henry VIII), and half-sister of the deceased King James V. After Lennox had seized the French money and artillery that was sent to Mary of Guise, she even offered the hand of her daughter Queen Mary in marriage.^[5] When the Parliament of Scotland rejected the Greenwich treaty, Lennox then changed sides, and supported King Henry VIII's military efforts to secure a marriage between Queen Mary and his son Prince Edward, in the War of the Rough Wooing.

In the summer of 1544, the Earl of Lennox plundered the Isle of Arran, and made himself master of the Isle of Bute and Rothesay Castle, with the support of eighteen ships and 800 men supplied by King Henry VIII. At the Battle of Glasgow Muir, his force of men managed to drive the first rank of the more numerous forces of Arran back into the second rank, and captured their cannon.^[6] However, the battle ended more favourably for the Regent Arran.^[7] There were about 300 slain on both sides, and Lennox himself withdrew to Dumbarton Castle.^[6] After a consultation with his English officers, Lennox attacked Dunoon Castle, as well as burning the nearby village and church. He subsequently then laid waste a large part of Kintyre, but as he had not succeeded in regaining possession of Dumbarton Castle, after it had been seized, Lennox retreated to his ships and sailed for England around 28 May 1544.

When the English army approached Edinburgh, before the Battle of Pinkie Cleugh, far to the west, a diversionary invasion of 5000 men was led by Thomas Wharton and Lennox on 8 September 1547. They took Castlemilk and burnt Annan, after a bitter struggle to capture its fortified church.^[8]

In 1544, Matthew Stewart married Lady Margaret Douglas, daughter of Archibald Douglas, 6th Earl of Angus and the Dowager Queen Margaret Tudor, who had a claim to the English throne. Their children were:

Lennox's grandchildren were:

For a time, Lennox and his family resided at Whorlton Castle in North Yorkshire, which had been granted, with the estate, to him by King Henry VIII. Later, at some point in the late 16th century, a house was built there by the Lennox family adjoining the northwest end of the castle's gatehouse.

In August 1548, Lennox made four promises to Mary of Guise in order for her assent to her daughter Queen Mary's marriage to Francis II of France. These were: that he and his friends and retainers would preserve the Catholic faith in Scotland; they would guard the Auld Alliance; Guise would remain guardian of the Queen; and he would punish all who supported the King of England.^[11]

Lennox returned to Scotland upon the urging of Queen Elizabeth I of England, during the marriage negotiations of Queen Mary of Scots in 1564. He quickly took up his position as the most powerful lord in the Glasgow area and was later instrumental in the marriage of his elder son, Lord Darnley, to Queen Mary. Whether Queen Elizabeth I had intended this (in order to eliminate the threat of a continental marriage), as is sometimes conjectured, remains doubtful. The Queen of England reacted with disapproval and had Lennox's wife Margaret confined in the Tower of London. By August 1565, William Cecil had heard that, the insolence of his son Darnley, had driven Lennox from the Scottish court.^[12]

After his elder son Darnley was murdered early in 1567, Lennox was the most ardent pursuant of justice against the lords who had conspired in the murder. He also became the main witness against Queen Mary, though her involvement in the murder, thought to have been carried out by her later husband, Lord Bothwell, is controversial.

In 1570, Lennox became regent for his grandson, King James VI of Scotland, but Queen Elizabeth's party declared war against him. He was shot dead next year in a skirmish, when the Queen's party attacked Stirling. The raid on Stirling on 4 September 1571 was led by the Earl of Huntly, Claude Hamilton, and the lairds of Buccleuch and Ferniehurst. Early reports said he was killed by his own party. William Kirkcaldy of Grange said the shot was fired by the Queen's party, and another account names David Bochinant as the assassin.^[13]