Robert Dudley, the favourite and courtier of Queen Elizabeth I, was the fifth son of John Dudley, Duke of Northumberland and Jane Guildford. At the age of eighteen, he married his first wife, Amy Robsart, whom he has been so often accused, but without sufficient evidence, of murdering in order to marry Elizabeth. He supported his father in the vain attempt to place Jane Grey on the throne in July 1553, was condemned to death for doing so, but pardoned in October 1554, went abroad and distinguished himself with his brother in the campaign against France in 1557. He received some kindness from Queen Mary's husband, Philip II of Spain, but his real fortunes began when Elizabeth, upon her accession, made him her Master of the Horse.

That Elizabeth loved Dudley and continued to love him, in spite of frequent quarrels, is a theory quite tenable; but the opposite theory, that she loved no-one at all, and merely employed Lord Robert as a stalking-horse against other suitors, is also tenable. Lady Amy Dudley died suddenly in 1560 at Cumnor Place, in North Berkshire, in circumstances that were at least suspicious, and part of the suspicion involved not only Lord Robert but the Queen as well. It is certain that the Queen carried open, but perhaps never secret flirtation with her Master of the Horse to the verge of impropriety. Him almost alone of her courtiers she rewarded with rich gifts of Crown lands and him, in a moment of weakness, she named Protector of the Realm in the event of her death, when she had her only recorded illness in 1562. That he, for his part, set himself forth to marry the Queen by all means in his power there is little doubt. He must have been considerably flabbergasted when the Queen gravely proposed him as a husband for her rival, Mary Queen of Scots. In order to fit him for the post, she created him, in 1564, Earl of Leicester.

Leicester, as prime favourite, was the incessant bugbear and terror of Cecil and the old Catholic nobles. Yet, he was obliged, sadly, to confess that Cecil could do more with his mistress in an hour than he could do in seven years; and so he gradually pulled away from his temporary connection with the Catholics and began to court the rising Puritan party in Church and State. Thus, he was always more friendly with Walsingham than with Cecil, and Walsingham's steady friendship is perhaps a point in his favour. Leicester certainly knew of the conspiracy of the Northern Earls in 1569 and may, perhaps, have been thinking of providing for his own safety in the event of its success; but, upon its failure, he had no difficulty in proving to Cecil that he had betrayed the conspirators. In1578 hemarried a wealthy widow, Lady Essex, thus becoming the step-father of Robert Devereux, 2nd Earl of Essex, Elizabeth's last favourite.

All this time, Leicester professed to be supporting the successive pretensions of the two French Valois princes to Elizabeth's hand. In 1585, Elizabeth's fondness induced her to entrust him with the English army sent to succour the Protestant Netherlands in their struggle with Spain. The Earl displayed great extravagance and great incompetence. He allowed the States-General to name him to the Governorship of the Provinces and thereby incurred much scolding from his mistress, and wasted much time, which would have been better employed in fighting the Spaniards, of which business Leicester did very little. He was recalled in November 1587, but his failure did not prevent the Queen from entrusting him with the command of her troops at Tilbury in August 1588, when the defeat of the Spanish Armada was yet hardly known. Early in the following month Leicester died suddenly. Perhaps the best thing that can be said for him is that he was a considerable patron of literature. Dudley was one of Elizabeth's lifelong friends; when he died in 1588, she was inconsolable.