Robert Dudley, Baron Denbigh, and Earl of Leicester, the favourite of Elizabeth, was born on the 24th of June in 1532 or 1533. He was the fifth son of John Dudley, Duke of Northumberland, who was executed in August 1553 for maintaining the claims of Lady Jane Grey, his daughter-in-law, to the crown. He was himself condemned to death for the part he took in the attempt of his father to place Lady Jane upon the throne; but on the intercession of the Lords of the Council was pardoned by Queen Mary, who received him into favour, and appointed him master of the English ordnance at the siege of St. Quentin, where his brother Henry was killed. On the accession of Elizabeth, Dudley soon became a great favourite of the Queen, who advanced him to the highest honours, and, there is little doubt, at one time contemplated a marriage with him. Leicester was a generous supporter of learning, and his letters show that he was himself possessed of considerable literary ability. Geoffrey Whitney, in his dedication of his Choice of Emblems to the Earl, mentions 'his zeale and honourable care of those that love good letters,' and states that 'divers, who are nowe famous men, had bin through povertie longe since discouraged from their studies if they had not founde your honour so prone to bee their patron.' Little is known respecting Leicester's library, which must have been a large and fine one, for many handsomely bound volumes which once belonged to it are found both in public and private collections. This dispersion of his books may probably be accounted for by the sale of his goods after his death, as mentioned by Camden in his Annals of the Reign of Elizabeth: 'But whereas he was in the Queen's debt, his goods were sold at a public Outcry: for the Queen, though in other things she were favourable enough, yet seldom or never did she remit the debts owing to her Treasury.' In the Notices of London Libraries, by John Bagford and William Oldys, it is stated: 'At Lambeth Palace over the Cloyster is a well-furnished library. The oldest of the books were Dudley's, Earl of Leicester.' Not more, however, than nine or ten which belonged to the Earl are to be found there now. Almost all his books have his well-known crest, the bear and ragged staff, stamped upon the covers, but a few of them bear his arms instead.

Leicester was suddenly seized with illness on his way to Kenilworth, and died at his house at Cornbury, in Oxfordshire, on the 4th of September 1588. The suddenness of his death gave rise to a suspicion that it was caused by poison; and Ben Jonson tells a story that he had given his wife 'a bottle of liquor which he willed her to use in any faintness, which she, not knowing it was poison, gave him, and so he died.' He was buried at Warwick.