The London Monster was the name given to an attacker of women in London between 1788 and 1790. Renwick Williams, a Welsh maker of artificial flowers, was arrested for the attacks in June 1790, given two trials and sent to Newgate Prison for six years. The Monster's modus operandi was to verbally abuse women with lewd and suggestive comments and then attack them with a knife, cutting the clothing and slicing into buttocks, thighs or chest. Other forms of attack included having knives attached to his knees, possibly attached as a claw-like device to his hands or having a sharp implement hidden in a nosegay—a small flower bouquet. Over fifty women reported attacks, sometimes several on the same day, including up to six reported attacks in one night. Such was the number of attacks, variety of methods and discrepancies in the descriptions of the attackers, that historians are unsure if the Monster was one man or several.
There were five attacks in March and May 1788, eight attacks between May and December 1789 and forty-four between January and June 1790. Most of the women attacked in the first two years were described as being young, elegant and attractive, although this changed in 1790 to a wider range of victims. In April that year the philanthropist John Julius Angerstein met friends and like-minded people and arranged a reward of 100 guineas (equivalent to £16,000 in 2023) for the capture and conviction of the Monster. Increasing press interest and lurid reporting led to a moral panic in London. Over thirty innocent men were taken to Bow Street Magistrates' Court with their accusers hoping to claim the reward; all were released. Some women wore protection in the form of a copper petticoat for the wealthy, or a cork lining or porridge pot for the less well-off.
Williams was arrested when one of the attacked women claimed to recognise him as the attacker. In the magistrates' hearing several victims of the Monster said they did not recognise Williams as their attacker, although some did. At the Old Bailey trial he was found guilty but sentencing was deferred to the December Court of Sessions. Before that Williams was told he had been charged and tried under the wrong offence, so the Court of Sessions would be a retrial. He was again found guilty, despite having an alibi for at least one of the attacks. There is doubt among some historians whether he was the attacker as no hard or forensic evidence was ever found. It is likely that copycat attacks took place, particularly as some of the assaults were recorded as being committed by a group of men.