Edmund de Mortimer, 5th Earl of March and 7th Earl of Ulster (6 November 1391 – 18 January 1425), was an English nobleman. A great-great-grandson of King Edward III of England, he was heir presumptive to King Richard II of England, his cousin once removed, when Richard II was deposed in favour of Henry IV. Edmund Mortimer's claim to the crown was the basis of rebellions and plots against Henry IV and his son Henry V, and was later taken up by the House of York in the Wars of the Roses, though Mortimer himself was an important and loyal vassal of Henry V and Henry VI. Edmund Mortimer was the last Earl of March of the Mortimer family.