His body was exhumed and executed after death

It is believed that Cromwell had kidney stones or other urinary/kidney issues. In 1658, after contracting malarial fever, Cromwell was once more afflicted with a urinary infection, which contributed to his decline and eventual death on Friday, September 3, at the age of 59. Coincidentally, this was also the anniversary of his victories during the Scottish campaign of 1650–1651 at Worcester and the Scottish town of Dunbar. Although it's believed that the infection that led to Cromwell's death caused him to develop septicemia, his grief over losing Elizabeth, his supposedly favorite daughter, to what is believed to have been cancer a month earlier undoubtedly accelerated his rapid decline. The funeral for Cromwell was modeled after King James I's, and his daughter was also given a lavish ceremony before being interred in a newly constructed vault in Henry VII's chapel at Westminster Abbey.

Oliver Cromwell's body, that of John Bradshaw, who presided over the High Court of Justice during King Charles I's trial, and that of Henry Ireton, who served as Cromwell's son-in-law and a general in the Parliamentary army during the English Civil War, were all removed from Westminster Abbey on January 30, 1661, in order to be "executed" and put on trial for high treason after their deaths. This symbolic day was picked to fall on Charles I's execution day twelve years earlier. The three bodies were beheaded at dusk after being hung in chains from the Tyburn gallows. The heads were then displayed at Westminster Hall on a 20-foot spike while the bodies were thrown into a common grave. They remained there until 1685 when a storm caused the spike to break and the heads to fall to the ground below.

Unusually, Cromwell allowed the King's head to be reattached to his body at the time of his execution so that his family could pay their final respects to the corpse. A soldier discovered Cromwell's own head after hiding it in his chimney. He left the artifact to his daughter on his deathbed. The head, referred to as "The Monster's Head," made an appearance in a "Freak Show" in 1710. The head was traded around for many years, its value rising with each exchange, until a Dr. Wilkinson decided to purchase it. The Wilkinson family presented the head to Sydney Sussex College, his alma mater, in 1960. It received a respectable burial in a hidden location on the college grounds.