Sir Robert Catlyn (died 1574) was an English judge and Chief Justice of the Queen’s Bench. He should not be confused with his cousin Richard Catlyn, a politician, who died in 1556.
The branch of the Catlyn family from which Robert Catlyn was descended was anciently seated at Raunds in Northamptonshire. The Northamptonshire Visitation of 1564 shows that he was the son of Thomas Catlyn of Leicestershire, who was the second son of Thomas Catlyn of Raunds and his wife, an heiress of the Barton family of Hargrave. The Raunds seat remained with the descendants of his uncle Robert Catlyn. He was born at Thrapston in Northamptonshire, and became a member of the Middle Temple, where he was elected reader in autumn, 1547. In October, 1555, he was admitted with six others to the degree of the coif; and on 4 November, in the following year, Philip and Mary appointed him one of their Serjeants.
Catlyn was raised to the bench as a judge of the Common Pleas on 10 October 1558, five weeks before the death of Queen Mary; and, like all the other judges, received a new patent the day after the accession of Queen Elizabeth. Previous to the following term, on the removal of the two Catholic chief justices, Catlyn was, on 22 January, promoted to the head of the court of King's Bench, in the place of Sir Edward Saunders. He was then knighted, and continued to preside as chief justice for the next sixteen years, with a high reputation for wisdom and gravity. That he was bold and independent also is apparent from a letter to Lord Burleigh, who had conveyed a message from the queen, complaining of his judgment in a suit in which the Earl of Leicester was a party, wherein he says he "dares not alter the ancient forms of court."