Harriet Howard, born Elizabeth Ann Haryett (1823–1865) was a mistress and financial backer of Louis Napoleon, later Napoleon III of France.
She was the daughter of a bootmaker and the granddaughter of the owner of the Castle Hotel in Brighton. At the age of fifteen, she ran off with Jem Mason, a well-known jockey, to live with him in London. As his red-headed mistress and an aspiring actress, she renamed herself Harriet Howard and was referred to as Miss Howard. At the age of eighteen, her next lover and patron was the married Major Mountjoy Martyn, Life Guards. Miss Howard bore him a son, Martin Constantin Haryett, who at his baptism was presented as the child of her parents. The grateful Major Martyn bestowed a fortune on her and their son.
At a party given by Lady Blessington in 1846, Miss Howard met Louis Napoleon, pretender to the throne of France, but at that time exiled in London. He moved in with her. With her wealth, she supported his efforts and conspiracies to return to France. Napoleon brought his two sons (Alexandre Louis Eugène and Louis Ernest Alexandre) from an affair at the prison at Ham into the household, where they were educated along with Martin.
In 1848 Napoleon returned to France and eventually became President. Miss Howard with the three boys moved to the rue de Cirque adjacent to the Palais de l'Élysée, where she kept herself in the background as his mistress. She had a powerful enemy in Napoleon's cousin Princess Mathilde to whom he was once engaged (1836) and who also had supported him financially. Miss Howard continued to support his aspirations to become emperor and largely financed his 1851 Coup d'état. One year later, after a confirming plebiscite, he became Napoleon III, Emperor of the French. Soon, he was on a search for an empress, and Miss Howard found herself cast aside. Napoleon, after having been rejected by Carola of Vasa of Sweden and other high-standing members of the nobility, chose Eugenie de Montijo. Miss Howard was sent away to Le Havre when Napoleon announced this marriage, and her secretary desk was emptied of its compromising letters.