Mary Howard, Duchess of Norfolk

Mary Howard, Duchess of Norfolk and 7th Baroness Mordaunt (c.1659–17 November 1705) was an English peer.

Biography Born Lady Mary Mordaunt, she was the only surviving child and heiress of Henry Mordaunt, 2nd Earl of Peterborough and Lady Penelope O'Brien, daughter of Barnabas O'Brien, 6th Earl of Thomond. On 8 August 1677, she married Henry Howard, Earl of Arundel. The Mordaunts being Protestant and the Howards Catholic, 'the wedding was perfectly private'. The earl succeeded his father as Duke of Norfolk in 1684. The Howard marriage was not a success and in 1685 the duke, himself a notorious rake, discovered his wife's liaison with Sir John Germain, 1st Baronet.

In 1692, facing financial difficulties and with the duchess pursuing her affair with Germain, the duke introduced a bill requesting a divorce into the House of Lords and sued Germain in the court of King's Bench.

The duchess succeeded to her father's barony in 1697.

The duke and duchess were finally divorced in 1700, leaving the duke free to remarry and have legitimate heirs. In the event the duke died unmarried a year later and Mary was then free to marry Germain. She died without children from either marriage in 1705.

Her memorial is in St Peter's Church, Lowick.