Stephen Martin Leake (5 April 1702 – 24 March 1773) was a numismatist and long-serving officer of arms at the College of Arms in London.
Though he eventually rose to the highest rank in the College, he was born as Stephen Martin and was the only son of Captain Stephen Martin, a naval officer, and his wife, Elizabeth. A relative left his considerable estate to Captain Martin on condition that he and his family adopt the additional name and arms of Leake. Shortly after the inheritance was completed in 1721, the family lost more than £20,000. The younger Leake was then holding a clerkship in the Navy Office, but the loss necessitated a search for a better position. His father attempted to buy a post in the Treasury but failed. Leake was admitted to Middle Temple and made a younger brother of Trinity House in 1723. In 1724 he became a deputy lieutenant for Tower Hamlets.
In 1725, the Order of the Bath was "revived" in Britain. Garter Principal King of Arms, Sir John Anstis arranged for Leake to be made an esquire to one of the knights. Anstis had met Leake while working with his family on the Royal Licence to change the family's name. The knight to whom Leake was attached was the Earl of Sussex, deputy Earl Marshal. In March 1726 Leake was elected a fellow of the Society of Antiquaries of London. He also published his essay Nummi Britannici Historia in that year covering the history of English coinage. This work was reissued in several editions during Leake's life.
Leake had made many powerful connections, but still lacked an appointment that would provide for his needs. Leake tried to use John Anstis to obtain a position at the College of Arms. Anstis used the opportunity of Leake's request to secure an appointment as Garter for his own son. After being embarrassed by Anstis, Leake assumed that he would be able to gain sympathy in other circles. In 1727 his connections gained him a spot as Lancaster Herald of Arms in Ordinary at the College. He was promoted Norroy King of Arms in December 1729.