Simon of Sudbury (d. June 14, 1381) was an Archbishop of Canterbury (1375 - 1381). He was born at Sudbury in Suffolk, studied at the University of Paris, and became one of the chaplains of Pope Innocent VI, who sent him, in 1356, on a mission to Edward III of England.

In October 1361 the pope appointed him Bishop of London, and he was soon serving the king as an ambassador and in other ways. In 1375 he succeeded William Whittlesey as archbishop of Canterbury, and during the rest of his life was a partisan of John of Gaunt.

In July 1377, he crowned Richard II, and in 1378 John Wycliffe appeared before him at Lambeth, but he only undertook proceedings against the reformer under great pressure.

In January 1380, Sudbury became chancellor of England, and the insurgent peasants regarded him as one of the principal authors of their woes. Having released John Ball from his prison at Maidstone, the Kentish insurgents attacked and damaged the archbishop's property at Canterbury and Lambeth; then, rushing into the Tower of London, they seized the archbishop himself. So unpopular was Sudbury that guards simply allowed the rebels through the gates.

Sudbury was dragged to Tower Hill and, on June 14 1381, was beheaded. His body was afterwards buried in Canterbury Cathedral. Sudbury rebuilt part of the church of St Gregory at Sudbury, and with his brother, John of Chertsey, he founded a college in this town; he also did some building at Canterbury. His father was Nigel Theobald, and he is sometimes called Simon Theobald or Tybald.

He introduced the Poll Tax in 1380, and the subsequent revolt was echoed when the tax was reintroduced in the 1980s. However, in the twentieth century the government quickly abandoned the scheme.

|- style="text-align: center;" | width="30%" |Preceded by:
The Lord Scrope of Bolton | width="40%" style="text-align: center;" |Lord Chancellor
1380–1381 | width="30%" |Succeeded by:
Hugh Segrave
(Keeper of the Great Seal)