Admiral Sir Thomas Williams GCB (c. 1761/62 – 8 October 1841) was a senior British Royal Navy officer of the late eighteenth and early nineteenth centuries, who served in numerous theatres during the American Revolutionary War, French Revolutionary Wars and Napoleonic Wars. As a young officer he fought at a number of battles in the Caribbean and as a frigate captain he was knighted for his actions at the Action of 8 June 1796 in which two French frigates were captured without a single man killed or wounded on Williams' ship HMS Unicorn. Later in his career, Williams commanded squadrons blockading the European coast and assisting the supply of the British Army during the Peninsula War.