||Anglesey, North Wales
||Roman suppression of Druid religion
|60 or 61 CE
||Boudica's attacks on the Romans
||Camulodunum (modern-day Colchester), Londinium and Verulamium (modern-day St Albans)
||70,000–80,000 (Mostly Britons)
||Forces led by Boudica, Queen of the British Iceni tribe, massacred both Romans and Britons in Camulodunum Londinium and Verulamium. Her forces were later defeated by the Romans at the Battle of Watling Street.
||Caedwalla's attack on Wihtwara
||Isle of Wight
||all but one
||According to Bede, King Caedwalla of Wessex "endeavoured to destroy all the inhabitants" of the island for reverting to paganism.
|13 November 1002
||St. Brice's Day massacre
||throughout the Kingdom of England
||The St. Brice's Day massacre was the mass killing of Danes in the Kingdom of England on orders of King Æthelred the Unready.
||Harrying of the North
||The North of England between the Humber and the Tees
||William the Conqueror's men burnt whole villages and slaughtered the inhabitants. Foodstores and livestock were destroyed so that anyone surviving the initial massacre would succumb to starvation over the winter.
|16 March 1190
||Massacre of the Jews at York
||'A wave of anti-Semitic riots culminated in the massacre of an estimated 150 Jews – the entire Jewish community of York – who had taken refuge in the royal castle where Clifford’s Tower now stands. The chronicler William of Newburgh described the rioters in York as acting “without any scruple of Christian conscientiousness” in wiping out the Jewish community'.
|30 March 1296
||Massacre of Berwick
||Berwick-upon-Tweed, Scotland (at the time)
||English troops massacred the civilian and military population, including women and children, after besieging the Scottish town.
|10-12 February 1355
||St Scholastica Day riot
||A riot culminating from tensions between the city of Oxford and the academic community belonging to the university.
|21 October 1490
||Massacre of Monzievaird
||Isle of Eigg, Scotland
According to Clanranald legend all occupants, bar one, of the Isle of Eigg's MacDonald clan were asphyxiated by their rival MacLeod clan in Massacre Cave on the south coast of the island. 
|28 May 1644
||An occurrence during the English Civil War in which Royalist Forces under Prince Rupert of the Rhine slaughtered a large population of the strongly Roundhead town of Bolton.
||Battle of Dunaverty
||More than 300 MacDougalls and MacDonald's followers, men, women and children, were slaughtered at Dunaverty after being promised quarter from the Covenanters.
|13 February 1692
||Massacre of Glencoe
||Glen Coe, Scotland
||Committed by the Clan Campbell under Captain Robert Campbell of Glenlyon, ostensibly due to irregularities concerning the swearing of an oath of allegiance to William II of Scotland.
|10 May 1768
||Massacre of St George's Fields
||Committed by the military during a riot.
|29 October 1797
||Massacre of Tranent
||Tranent, East Lothian, Scotland
||Townsfolk, including women and children, were killed by members of the Cinque Ports Dragoons, a fencible cavalry regiment, during a protest against the Act of Parliament to raise a Scots militia by a form of conscription.
|16 August 1819
||Committed by the military during a large outdoor protest.
|May - 7 June 1831
||Merthyr Tydfil, Wales
||Described by historian John Davies as "the most ferocious and bloody event in the history of industrialized Britain", the rebellion in Merthyr Tydfil and surrounding areas broke out following protests against falling wages, the price of bread, and forced redundancy. During the bloodiest incident, highland troops sent to re-take Merthyr fired on protesters during a fight against a large crowd.
|4 November 1839
||Led by John Frost, between 1,000 and 5,000 Chartist sympathisers armed with home-made weapons marched on Newport, intent on liberating fellow Chartists who had been reportedly taken prisoner. About 22 demonstrators were killed when troops opened fire on them. The leaders of the rebellion were convicted of high treason, and sentenced to transportation for life.
|12/13 August 1842
||Preston Strike of 1842
||Preston, Lancashire, England
||The Mayor Samuel Horrocks read the Riot Act. This gave local authorities the right to use force if necessary to disperse unlawful assemblies and stop riots. When violence escalated and the crowd did not disperse the military then fired, shooting at least eight men.
|22 February 1972
||A car bomb outside the headquarters of the British Army's 16th Parachute Regiment by Official IRA member Noel Jenkinson.
|4 February 1974
||M62 coach bombing
||West Yorkshire, England
||A bombing on a coach carrying servicemen and their families by the Provisional IRA.
|5 October 1974
||Guildford pub bombings
||Two bombs detonated in two separate Guildford pubs by the Provisional IRA who targeted them because they were popular with British servicemen.
|21 November 1974
||Birmingham pub bombings
||Two bombs detonated in two separate Birmingham pubs by the Provisional IRA.
|16 August 1980
||Denmark Place fire
||Camden, London, England
||An arson attack against a night club on Denmark Street by patron who was angry at being barred from the club for arguing with a bartender. Described as the deadliest mass murder in modern British history.
|19 August 1987
||A spree shooting/murder–suicide.
|21 December 1988
||A bombing on the Pan Am Flight 103 over Lockerbie by Libyan terrorist Abdelbaset al-Megrahi, the wreckage of the destroyed plane fell onto the town of Lockerbie. All passengers and crew members on the flight died, and eleven people on the ground.
|13 March 1996
||Dunblane school massacre
||A school shooting/murder–suicide.
|7 July 2005
||7 July 2005 London bombings
||A series of coordinated terrorist suicide attacks occurred throughout London between 08:50-09:47 in the morning. It was the United Kingdom's worst terrorist incident since the 1988 Lockerbie bombing as well as the country's first ever suicide attack.
|2 June 2010
||A killing spree/murder–suicide.
|22 May 2017
||2017 Manchester Arena bombing