John of Eltham, Earl of Cornwall

John of Eltham (1316–1336), Earl of Cornwall, was the second son of Edward II and Isabella of France and younger brother of Edward III. Created earl in 1328, he served as Guardian of the Realm during Edward III's absences.

In 1333 he was a leading commander at Halidon Hill, where the Scots were crushingly defeated, and he later led troops in south-western Scotland. He died at Perth, probably of fever, just after turning twenty and was buried in Westminster Abbey.