Thomas Howard, 5th Duke of Norfolk was an English nobleman who from 1645 was deemed a lunatic. Born the eldest son of Henry Howard, 15th Earl of Arundel, Howard left England to study at Utrecht University at the start of the English Civil War. While visiting his paternal grandfather at Padua in 1645 he contracted a fever that damaged his brain. He was declared insane and confined in Padua with a physician caring for his needs. He became Earl of Arundel upon the death of his father in 1652.

Henry Frederick Howard, 15th Earl of Arundel PC(Ire), styled Lord Maltravers until 1640, and Baron Mowbray from 1640 until 1652, was an English nobleman, chiefly remembered for his role in the development of the rule against perpetuities.