Mary Ann Cotton (née Robson; 31 October 1832 – 24 March 1873) was an English convicted murderer who was executed for poisoning her stepson.

Despite her sole conviction for murder, she is believed to have been a serial killer who killed many others including 11 of her 13 children and three of her four husbands for their life insurance policies.

At the time of her trial, The Northern Echo published an article containing a description of Mary Ann as given by her childhood Wesleyan Sunday school superintendent at Murton, describing her as "a most exemplary and regular attender", "a girl of innocent disposition and average intelligence", and "distinguished for her particularly clean and tidy appearance.

"[2] Soon after the move, Mary Ann's father fell 150 feet (46 m) to his death down a mine shaft at Murton Colliery in February 1842.

Her father's body was delivered to her mother in a sack bearing the stamp 'Property of the South Hetton Coal Company'.

In 1852, 20-year-old Mary Ann married colliery labourer William Mowbray at Newcastle upon Tyne register office; they soon moved to South West England.

Soon after Mowbray's death, Mary Ann moved to Seaham Harbour, County Durham, where she struck up a relationship with Joseph Nattrass.

A month later, when James's baby John died of gastric fever, he turned to his housekeeper for comfort and she became pregnant.

Robinson, meanwhile, had become suspicious of his wife's insistence that he insure his life; he discovered that she had run up debts of £60 behind his back and had stolen more than £50 that she had been expected to bank.

Cotton and Mary Ann were bigamously married on 17 September 1870 at St Andrew's, Newcastle-Upon-Tyne and their son Robert was born early in 1871.

Soon after, Mary Ann learnt that her former lover, Joseph Nattrass, was living 48 kilometres (30 mi) away in the County Durham village of West Auckland, and was no longer married.

However, Richard Quick Mann, a custom and excise man specialising in breweries, has been found in the records; his may be the real name of Mary Ann Cotton's lover.

Mary Ann's downfall came when a parish official, Thomas Riley, asked her to help nurse a woman who was ill with smallpox.

Riley went to the village police and persuaded the doctor to delay writing a death certificate until the circumstances could be investigated.

Mary Ann claimed to have used arrowroot to relieve his illness and said Riley had made accusations against her because she had rejected his advances.

Then the local newspapers latched on to the story and discovered Mary Ann had moved around northern England and lost three husbands, a lover, a friend, her mother, and 11 children, all of whom had died of stomach fevers.

She was charged with his murder, although the trial was delayed until after the delivery in Durham Gaol on 7 January 1873 of her thirteenth and final child, whom she named Margaret Edith Quick-Manning Cotton.

A Mr Aspinwall was first considered but the Attorney General, Sir John Duke Coleridge, whose decision it was, chose his friend and protégé Charles Russell.

The defence in the case was handled by Thomas Campbell Foster, who argued during the trial that Charles had died from inhaling arsenic used as a dye in the green wallpaper of the Cotton home.

Mary Ann Cotton was hanged at Durham County Gaol on 24 March 1873 by William Calcraft; she died, not from her neck breaking, but by strangulation caused by the rope being rigged too short, possibly deliberately.

[8] The drama was inspired by the book Mary Ann Cotton: Britain's First Female Serial Killer by David Wilson, a criminologist.

[9] The Mary Ann Cotton case was partly dramatized on an episode of the 2022 BBC Radio podcast series Lucy Worsley's Lady Killers.

[10] Also seen on Martina Cole's Lady Killers 2008 Mary Ann Cotton, she's dead and she's rotten Lying in bed with her eyes wide open.