Edmund of Langley, 1st Duke of York, (June 5, 1341 - August 1, 1402) was a younger son of King Edward III of England, the fourth of the five sons of the King who lived to adulthood. He was the founder of the House of York, but it was through the marriage of his younger son, Richard, that the Yorkist faction in the Wars of the Roses made its claim on the throne.

Like so many medieval princes, Edmund gained his identifying nickname from his birthplace: Kings Langley in Hertfordshire. At the age of twenty-one, he was created Earl of Cambridge. In 1385, Edmund was created Duke of York.

His first wife, Isabella, was the daughter of Pedro "the Cruel" of Castile. They had two sons, Edward (killed in action at the Battle of Agincourt) and Richard, Earl of Cambridge (executed for treason by Henry V), as well as a daughter, Constance (an ancestor of queen Anne Neville).

After Isabella's death in 1392, Edmund married Joan de Holland, his second cousin twice removed (she was a granddaughter of Joan of Kent; Joan of Kent and Edmund were both grandchildren of Edward II). Langley and Joan produced no children.

Although marriages within the royal family and between royal families are the rule, it is interesting to note Edmund's marital ties to his older brother, John of Gaunt. Edmund's first wife was the sister of John of Gaunt's wife, and Edmund's second wife was the sister of John of Gaunt's daughter-in-law.

Death

Edmund of Langley died in his birthplace, and was buried there, in the church of the mendicant friars. His dukedom passed to his eldest son, Edward.

|- style="text-align: center;" | width="30%" |Preceded by:
The Lord Beaumont | width="40%" style="text-align: center;" |Lord Warden of the Cinque Ports
1396–1398 | width="30%" |Succeeded by:
The Marquess of Dorset