Walter Devereux, 1st Earl of Essex
Walter Devereux was the eldest son of Sir Richard Devereux, who was created a Knight of the Bath on 20 February 1547 and died that same year, in the lifetime of his father, The 1st Viscount Hereford. Walter Devereux's mother was Lady Dorothy Hastings, daughter of The 1st Earl of Huntingdon and Anne Stafford, said to have been a mistress of Henry VIII. Through his paternal ancestry he was related to the Bourchier family, to which previous Earls of Essex had belonged: John Devereux, son of Walter Devereux who died at the Battle of Bosworth, married Cecily Bourchier, sister of Henry Bourchier, 2nd Earl of Essex.
Walter Devereux, 1st Viscount Hereford
Devereux was first married to Lady Mary Grey (1491- 22 February 1538) prior to his father's death in May 1501, and was pardoned on 15 December 1503 for having married in his father's lifetime and when under marriageable age. She was a daughter of Thomas Grey, 1st Marquess of Dorset and his second wife Cecily, "suo jure" Baroness Harington and Bonville, daughter and heiress of William Bonville, 6th Baron Harington by his wife Katherine Neville, "suo jure" Baroness Hastings. Her maternal grandparents were Alice Montagu, 5th Countess of Salisbury and Sir Richard Neville, "jure uxoris" Earl of Salisbury.