Kazuo Nakanishi (中西 一男, Nakanishi Kazuo; October 25, 1922 – September 1, 2003) was briefly the leader of the Yamaguchi-gumi yakuza syndicate in the chaotic years of the Yama–Ichi War. He was also the founder and 1st kumicho of the Nakanishi-gumi.

Tse Chi Lop (Chinese: 謝志樂, born 25 October 1963) is a Chinese and Canadian gangster, drug trafficker and drug cartel leader. Before his arrest, Tse was the alleged drug lord behind Asia-Pacific based international crime syndicate Sam Gor, also referred to as "The Company", and a former member of the Hong Kong, Toronto and Vancouver-based triad crime group Big Circle Gang.

Arnfinn Nesset (25 October 1936 – 2 December 2025) was a Norwegian nurse and nursing home manager who was a convicted serial killer. His crimes include the murders of at least 22 people, as well as attempted murder, document forgery, and embezzlement.

Miguel Cortés Miranda (25 October 1984 – 13 April 2025), known as The Monster of Iztacalco (Spanish: El monstruo de Iztacalco), was a Mexican suspected serial killer and bacteriological chemist who was implicated in the rape and murder of at least three young girls and women in Mexico City, all of which occurred between 2012 and 2024.

James Brown Miller (October 25, 1861 – April 19, 1909), also known as "Killin' Jim", "Killer Miller" and "Deacon Jim", was an American outlaw and title-holder gunfighter of the American Old West, said to have killed 12 people during gunfights. Miller was referred to by some by the alias "Deacon Jim" because he regularly attended the Methodist Church, and he did not smoke or drink.

Marc Lépine (French: [maʁk lepin]; born Gamil Rodrigue Liess Gharbi; October 26, 1964 – December 6, 1989) was a Canadian misogynistic terrorist and mass murderer who perpetrated the École Polytechnique massacre where he murdered 14 women and wounded another 10 women and 4 men at École Polytechnique de Montréal on December 6, 1989.

John Tarleton (1718–1773) was an English ship-owner and slave-trader, and Mayor of Liverpool in 1764.

Umar Farooq Zahoor (Punjabi: عمر فاروق ظہور; born 1975) is a Norwegian-born Pakistani businessman, crime boss, and convicted felon. Since 2010, he is a fugitive sought in Norway for financial crimes.

Anthony Rene Wimberly (né Lee; born October 26, 1962) is an American criminal and serial killer. Between December 1984 and January 1985, he murdered three women in Oakland for the purpose of robbery, as well as raping a 12-year-old girl.

On 15 March 2019, two consecutive terrorist mass shootings took place in Christchurch, New Zealand. They were committed during Friday prayer, first at the Al Noor Mosque in Riccarton, at 1:40 p.m.

John Joseph Gotti Jr. ( GOT-ee, Italian: [ˈɡɔtti]; October 27, 1940 – June 10, 2002) was an American mafioso and boss of the Gambino crime family in New York City.

Sun Xiaoguo (born Chen Guo and also known by his alias Li Linchen; 27 October 1977 – 20 February 2020), was a serial child rapist and gang leader from Kunming, China. He was known for the brutality of his crimes as well as his evasion of justice.

On August 4, 2019, 24-year-old Connor Betts shot and killed nine people, including his brother, and wounded 17 others near the entrance of the Ned Peppers Bar in the Oregon Historic District of Dayton, Ohio, United States. Betts was fatally shot by responding police officers 32 seconds after the first shots were fired.

Thomas John Ley (28 October 1880 – 24 July 1947) was an Australian politician who was convicted of murder in England. He is widely suspected to have been involved in the deaths of a number of people in Australia, including political rivals.

Leonard Thomas Lake (October 29, 1945 – June 6, 1985), also known as Leonard Hill and a variety of other aliases, was an American survivalist and serial killer who raped, tortured and murdered an estimated eleven to twenty-five victims with his accomplice Charles Ng at a remote cabin near Wilseyville, California, 150 miles east of San Francisco, between 1983 and 1985. Lake was never convicted of murder, as he swallowed cyanide pills that he had sewn into his clothing and died four days after his arrest.

Russell Alfred Bufalino (; born Rosario Alfredo Bufalino, Italian: [roˈzaːrjo alˈfreːdo bufaˈliːno]; October 29, 1903 – February 25, 1994) was an Italian-American mobster who became the crime boss of the Northeastern Pennsylvania Italian-American Mafia crime family known as the Bufalino crime family, which he ruled from 1959 to 1994. He was a cousin of attorney Bill Bufalino, the longtime counsel for Jimmy Hoffa.

Margie Velma Barfield (née Bullard; October 29, 1932 – November 2, 1984) was an American serial killer who was convicted of one murder but was linked to seven murders in total. She became the first woman in the United States to be executed after the resumption of capital punishment in 1976, and the first since 1962.

John Frank Hickey (October 29, 1865 – May 8, 1922) was an American child molester and serial killer. Due to the postcards he mailed to the police and media, he was dubbed The Postcard Killer.

Franz Joseph Hermann Michael Maria von Papen, Erbsälzer zu Werl und Neuwerk (German: [ˈfʁants fɔn ˈpaːpn̩] ; 29 October 1879 – 2 May 1969) was a German politician, diplomat, army officer and Prussian nobleman. A national conservative, he served as Chancellor of Germany in 1932, and then as Vice-Chancellor under Adolf Hitler from 1933 to 1934.

Larry Gene Bell (October 30, 1949 – October 4, 1996) was an American serial killer who abducted, raped, and murdered at least three women and girls in the Carolinas from 1984 to 1985. In addition to this, Bell remains the prime suspect in at least one disappearance.

Mikhail Yuryevich Malyshev (Russian: Михаил Юрьевич Малышев; 31 October 1965 – 19 December 2025), known as the Perm Cannibal (Russian: Пермский людоед), was a Russian murderer, cannibal and possible serial killer who was convicted of murdering, dismembering and eating the remains of two acquaintances in the city of Perm between 1997 and 1998. He was also suspected of six similar murders for which he was never charged.

Robert Charles Browne (born October 31, 1952) is an American murderer who is currently serving two life sentences for the murders of two teenage girls in Colorado Springs, Colorado, committed in 1987 and 1991, respectively. A few years into his sentence, he sent letters to the El Paso County Sheriff's Office in which he claimed to be a serial killer who has killed approximately 48 or 49 people since 1970 across several states.

Cayetano Santos Godino (31 October 1896 – 15 November 1944), also known as El Petiso Orejudo (Spanish: The Big-Eared Midget), was an Argentine serial killer and arsonist who murdered four children, attempted to kill seven others, and set fire to seven buildings, psychologically enjoying fires.

Martin Lecián (31 October 1900 – 6 October 1927) was a Czech serial killer who murdered 3 policemen and a prison officer and attempted to kill 7 other policemen. He was executed on 6 October 1927.

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.