The eldest son of Sir Robert Killegrew, Knt. chamberlain to the Queen, was born at the Manor of Hanworth, near Hampton-Court, in the month of May, 1605. He became a gentleman commoner in St. John's College in Midsummer term 1622; where continuing about three years he travelled beyond seas, and after his return, was made governor of Pendennis castle, and of Falmouth haven in Cornwall, with command of the militia in the west part of that county. After this he was called to attend King Charles I. as one of his gentlemen ushers of his privy chamber; in which employment he continued till the breaking out of the great rebellion; and had the command given him of one of the two great troops of horse that guarded the King's person, during the whole course of the war between his Majesty and his Parliament. Our author was in attendance upon the King when the court resided at Oxford, and was created doctor of the civil laws 1642;[1] and upon the ruin of the King's affairs, he suffered for his attachment to him, and compounded with the republicans for his estate. Upon the restoration of King Charles II. he was the first of his father's servants that he took any notice of, and made him gentleman-usher of his privy chamber: the same place he enjoyed under the deceased King. Upon Charles IId's marriage with Donna Catherina of Portugal, he was created his Majesty's first vice chamberlain, in which honourable station he continued twenty-two years. His dramatic works are, 1. Orinasdes, or Love and friendship, a tragi-comedy. 2. Pandora, or the Converts, a Comedy. 3. Siege of Urbin, a Tragi-Comedy. 4. Selindra, a Tragi-Comedy. All these plays were printed together in folio, Oxon 1666. There is another play ascribed to our author, called the Imperial Tragedy, printed in 1699; the chief part was taken out of a Latin play, and much altered by him for his own diversion; tho' upon the importunity of his friends, he was prevailed upon to publish it, but without his name. The plot is founded upon the history of Zeno, the 12th emperor of Constantinople after Constantine. Sir William Killegrew's plays have been applauded by men very eminent in poetry, particularly Mr. Waller, who addresses a copy of verses to him upon his altering Pandora from a tragedy into a comedy, because not approved on the stage. Sir William has also a little poem extant, which was set to music by Mr. Henry Lawes, a man in the highest reputation of any of his profession in his time. Mr. Wood says, that after our author had retired from court in his declining age, he wrote The Artless Midnight Thoughts of a Gentleman at Court; who for many years built on sand, which every blast of cross fortune has defaced; but now he has laid new foundations, on the rock of his salvation, &c. London 1684. It is dedicated to King Charles II. and besides 233 thoughts in it, there are some small pieces of poetry.