- Si·mon de [see-mawn duh] /siˈmɔ̃ də/, c1160–1218, French leader of the crusade against the Albigenses.
- his sonSimon de, Earl of Leicester,1208?–65, English soldier and statesman: leader of the Barons’ War.
- Simon de, Earl of Leicester. ?1208–65, English soldier, born in Normandy. He led the baronial rebellion against Henry III and ruled England from 1264 to 1265; he was killed at Evesham