Henrietta Ponsonby, Countess of Bessborough (16 June 1761 – 11 November 1821), born Lady Henrietta Frances Spencer (generally called Harriet), was the wife of Frederick Ponsonby, 3rd Earl of Bessborough, and mother of the notorious Lady Caroline Lamb. Her father, John Spencer, 1st Earl Spencer, was a great-grandson of John Churchill, 1st Duke of Marlborough. Her sister was Georgiana Cavendish, Duchess of Devonshire.
Being the youngest child, Harriet was often left in England when her parents and older sister Georgiana would visit the continent for her father's health. As a child, Harriet was frail and sickly, which led her mother to send her abroad for schooling, thinking that foreign air would help strengthen her. However, she grew into a young woman of exceptional beauty and intelligence, witty, well-read and self-assured.
On 27 November 1780, Harriet married Viscount Duncannon, an Anglo-Irish nobleman who later became The 3rd Earl of Bessborough. Their marriage was a difficult one; because Harriet and her husband were both avid gamblers, they often found themselves in debt. Frederick, Lord Bessborough, was also known to be abusive of Harriet, often humiliating her at public gatherings, as well as demanding that she find money to pay for the debts which he had incurred. In 1790, her husband began divorce proceedings, but, under intense pressure from both families, agreed to drop them. Their marriage produced four children: John William, later 4th Earl of Bessborough; Frederick Ponsonby; Lady Caroline Ponsonby, more commonly known by her married name as Lady Caroline Lamb; and William Ponsonby, who became The 1st Baron de Mauley.
Harriet had numerous lovers during her marriage; as she once remarked "I can never love a little". Among her more notable lovers were Richard Brinsley Sheridan, the playwright and Whig politician, and Granville Leveson-Gower, 1st Earl Granville, who became her most enduring lover.
Her affair with Granville produced two illegitimate children: Harriet Emma Arundel Stewart, wife of George Godolphin Osborne, 8th Duke of Leeds (though she died in 1852 before he succeeded to the title), and George Stewart. Harriet managed to hide her pregnancies from her husband; this was less difficult in an era when the aristocracy might make extended visits of many months abroad or to friends' country homes. She later sadly remarked that for seventeen years she had "loved [Granville] to idolatry." However, she came to believe that he loved her least of all the men in her life, "although I once believed otherwise". Recognizing his need to marry for purposes of his political career, she did not oppose, and in fact facilitated, Granville's marriage to her niece, Lady Harriet Cavendish ('Harryo') in 1809.
Of her younger admirers, her favourite was The Hon. William Lamb (who succeeded as The 2nd Viscount Melbourne in 1828), although he then fell in love with her daughter Caroline. Although Harriet was anxious for Caroline to marry early, she had misgivings (which would come to be entirely justified) as to whether William and Caroline were well suited. However, due to her fondness for William, she gave her consent to their marriage.
Richard Sheridan's feelings for her became an obsession. He distressed her greatly just before his death by saying that he hoped his ghost would haunt her; she asked him if he had not done enough through his life to make her unhappy, without wishing to harm her further?
Harriet often accompanied her sister to political events as well as soirees. She was also very close to her sister Georgiana's best friend, Lady Elizabeth Foster, with whom she often was seen in public.
Harriet died on 11 November 1821, in Florence, Italy at the age of 60, following the death of her youngest grandchild, Henry, in Parma. According to Lord David Cecil, she died peacefully and without regrets, worn out as she was by a life of emotional turmoil.
Cecil describes her as a woman of "indescribable distinction".
