Lieutenant General Sir Thomas Picton GCB (24 August 1758 – 18 June 1815) was a British Army officer who fought in a number of campaigns for Britain in the Napoleonic wars. According to the historian Alessandro Barbero, Picton was "respected for his courage and feared for his irascible temperament." The Duke of Wellington called him "a rough foul-mouthed devil", but very capable.

Picton came to public attention initially for his alleged cruelty during his governorship of Trinidad, as a result of which he was put on trial in England for illegally torturing a woman. Though he was convicted, the conviction was later overturned.

He is chiefly remembered for his exploits under Wellington in the Iberian Peninsular War, during which he fought in many engagements displaying great bravery and persistence. He was killed fighting at the Battle of Waterloo, during a crucial bayonet charge in which his division stopped d'Erlon's corps' attack against the allied centre left. He was the most senior officer to die at Waterloo.