Thomas, 2nd Earl of Lancaster (c. 1278 – 22 March 1322) was an English nobleman of the first House of Lancaster, a cadet branch of the royal Plantagenet dynasty. He held the titles of Earl of Lancaster, Leicester, and Derby from 1296 until his death in 1322, and also those of Earl of Lincoln and Salisbury jure uxoris from 1311 to 1322. As one of the most powerful barons in England, Thomas became a leading figure in the baronial opposition to his first cousin, King Edward II.