William Howard, 1st Baron Howard of Effingham (c. 1510 – 1573), English lord high admiral, was the son of the Thomas Howard, 2nd Duke of Norfolk by his second wife Agnes Tilney (d. May, 1545), daughter of Hugh Tilney of Boston and Hugh Tilney of Boston and Eleanor Eleanor Tailboys. Agnes should not be confused with Elizabeth Tilney (d. 4 April, 1497), the first wife of Thomas Howard.

He was popular with Henry VIII of England, and was deputy Earl Marshal at the coronation of Anne Boleyn. Anne was daughter to his elder half-sister Elizabeth Boleyn, Countess of Wiltshire.

William was sent on missions to Scotland and France. But in 1541, William was charged with abetting Catherine Howard, his niece and fourth Queen consort of Henry VIII, in committing adultery, and was convicted of misprision of treason, but pardoned.

He was made governor of Calais in 1552 and Lord High Admiral in 1553. He was created Baron Howard of Effingham in 1554 for his defence of London in the rebellion of Thomas Wyatt the younger against Mary I of England.

He befriended the Princess Elizabeth Tudor, but his popularity with the navy saved him from the resentment of Mary. When the princess became Queen Elizabeth I, William had great influence with her and filled several important posts.

William married Margaret Gamage, daughter of Sir Thomas Gamage and Margaret St. John. His son Charles Howard, 2nd Baron Howard of Effingham is famous in English naval history and was created Earl of Nottingham. The later Earls of Effingham descended from his younger son William Howard. His daughter Douglas Howard [sic] was born in 1545, married first John Sheffield, 2nd Baron Sheffield of Butterwick , secondly (in secret) Robert Dudley, 1st Earl of Leicester and thirdly Edward Stafford.

His descendant (through his son William) Francis Howard, 5th Baron Howard of Effingham (d. 1695), inherited the barony of Howard of Effingham on the death of his cousin, Charles Howard, 3rd Earl of Nottingham, 4th Baron Howard of Effingham in 1681.

Francis' son, Francis Howard, 1st Earl of Effingham (1683–1743) was created earl of Effingham in 1735. This earldom became extinct on the death of Richard Howard, 4th Earl of Effingham in 1816 but was created again in 1837 in favor of Kenneth Alexander Howard, 1st Earl of Effingham (1767–1845) another of his descendants, who had succeeded to the barony of Howard of Effingham in 1816.

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