William was the son of unknown parents. The date and place of his birth have not been found.
His wife was Anne Plantagenet. They were married, but the date and place have not been found. Their only known child was William (1407-1470).
Note 1
!Stylename: Bouchier, William, 1st Count of Eu
!Source: https://www.1820settlers.com/documents/Bowker_Bourchier/data/fam203.html
Family of William Bourchier - 1st Count of Eu and Anne Plantagenet - of Gloucester, Countess of Stafford and Eu
Husband: William Bourchier - 1st Count of Eu
Wife: Anne Plantagenet - of Gloucester, Countess of Stafford and Eu
Children: Henry Bourchier - 5th Baron Bourchier, 2nd Count of Eu, 1st Viscount Bourchier, 1st Earl of Essex
William Bourchier - 1st Baron Fitzwaryn
John Bourchier - 1st Baron Berners
Thomas Bourchier - Cardinal of Canterbury Cathedral
Eleanor Bourchier - Duchess of Norfolk