"El Chapo" or "Shorty" (he stands 5ft 6in tall) heads an international drug trafficking organisation, the Sinaloa Cartel, and became Mexico's top drug kingpin in 2003 after the arrest of his rival Osiel Cárdenas of the Gulf Cartel. Appears simultaneously on Forbes's lists of the world's most powerful, most wealthy and most wanted men. Ruthless and determined, Guzmán has succeeded in turning Ciudad Juárez, a strategic smuggling point that overlooks El Paso, Texas, into one of the murder capitals of the world through mind-numbingly brutal battles against both the Gulf and La Linea cartels, leaving thousands dead. A faction from La Linea has recently defected to Shorty's side; a local street gang, the Mexicles, has sub-contracted its services in killing, kidnapping, drug dealing and extorting; and even elements of the police and army seem to have thrown their lot in with him. Sinaloa smuggles many tonnes of cocaine from Colombia through Mexico into the United States, and is also heavily involved in Mexican methamphetamine, marijuana and heroin.
2 Dawood Ibrahim Head of Indian crime network
Dawood Ibrahim, Indian gangster.
The most wanted man in India heads up a 5,000-strong organised crime network called the D-Company that is involved in everything from drugs trafficking to contract killing in Pakistan, India and the UAE. Currently on the Interpol wanted list for organised crime and counterfeiting, besides association with al-Qaida. According to Washington, Ibrahim uses the same smuggling routes as al-Qaida and has worked with both the mother organisation and its offshoot Lashkar-e-Taiba, responsible for the November 2008 Mumbai attacks. He is also suspected in the 1993 Mumbai bombings that killed 257 people and wounded 713. Like Bin Laden, Ibrahim may well be based in Pakistan.
3 Semion Mogilevich Russian 'boss of bosses'
Semion Mogilevich Photograph: Rex Features
Arrested in Russia for tax evasion in 2008, Ukrainian-born Mogilevich was released in 2009. Wanted in the US in connection with a $150m share fraud; believed by both European and US law enforcement agencies to be the "boss of bosses" of most Russian mafia syndicates in the world. Nicknames include "Don Semyon" and "The Brainy Don"; often described as "the most dangerous mobster in the world".
4 Matteo Messina Denaro Cosa Nostra kingpin
Matteo Messina Denaro. Photograph: EPA
Sicilian mafioso who has effectively taken control of Italy's Cosa Nostra following the arrest of Bernardo Provenzano and other leading mobsters. Nicknamed "Diabolik", after an Italian comic-book character. Known for his fast lifestyle, Porsches and Rolex watches, he has been on the run since 1993.
5 Alimzhan Tokhtakhounov Uzbek mobster
Alimzhan Tokhtakhounov, Uzbekistan-born mobster.
Major Russian mobster originally from Uzbekistan and apparently known as "Taiwanchik" for his Asian appearance. Washington describes him as a "major figure in international Eurasian organised crime" engaged in "drug distribution, illegal arms sales and trafficking in stolen vehicles." He is even alleged to have bribed the figure skating judges in the 2002 Winter Olympics.
6 Felicien Kabuga Mastermind of genocide
Felicien Kabuga, accused of genocide. Photograph: KRT
Accused of bankrolling the Rwandan genocide, inciting bloodshed through his radio station and even supplying the machetes and hoes used in the massacres, Kabuga is wanted by the International Criminal Tribunal for Rwanda for "serious offences under the 1949 Geneva Conventions, crimes against humanity and genocide" in connection with the massacre of more than 800,000 Rwandan men, women and children in 100 days of terror in 1994. Allegedly hiding in Kenya.
7 Joseph Kony Ugandan guerrilla leader
Joseph Kony. Photograph: Reuters
Head of the Lord's Resistance Army, a guerrilla group engaged in a violent campaign to establish theocratic government in Uganda. Has also operated in the Democratic Republic of Congo, and Sudan, abducting an estimated 66,000 children and displacing more than two million people since 1986. The International Criminal Court has indicted him on 33 charges including crimes against humanity and war crimes.
8 James 'Whitey' Bulger Old-school US mobster
James 'Whitey' Bulger
The ever-so-slightly embarrassing older brother of William Michael Bulger, a former president of the Massachusetts state senate and the University of Massachusetts, Bulger was part of the Winter Hill Gang, a Boston-based Irish-American crime network that for many years ran illicit drugs and extortion rackets. Pursued by the FBI for more than a decade for racketeering, murder (his name has been linked to 19 killings from the early 70s up to the mid-80s), conspiracy to commit murder, extortion, conspiracy to commit extortion, money laundering and narcotics distribution. Bulger's wealth is estimated at between $30m and $50m (£18m-£30m), cash he is said to be using to evade arrest with his longtime girlfriend. Last confirmed sighting was in London in 2002. There is a reward of $2m for information leading to his arrest
9 Omid 'Nino' Tahvili Head of Canadian crime group
Omid 'Nino' Tahvili.
Head of a Persian organised crime network in Canada linked to assorted Triads and other global criminal groups. Arrested on charges of torturing a relative of a man he suspected had stolen a chunk of his organisation's illicit drugs money, he walked out of a Canadian maximum security prison in a janitor's uniform in November 2007 after promising to pay a guard to let him out (he never forked up). US law enforcement wants to talk to him about a fraudulent telemarketing business that targeted people in the US, stealing some $3m from hundreds of victims, most of them elderly.
10 ? Ayman al-Zawahiri Al-Qaida number two
Ayman al-Zawahiri, deputy to Osama bin Laden. Photograph: AP
Born in June 1951 into a prominent upper-middle class family in Cairo, Zawahiri was the final "emir" of Egyptian Islamic Jihad, which he merged into al-Qaida in 1998. Reportedly a qualified surgeon, he speaks Arabic, English and French. According to former al-Qaida members, Zawahiri has worked with al-Qaida since the organisation's earliest beginnings. He is often described as Bin Laden's right-hand man, and by some as the "real brains" of al-Qaida. The friendship between the two men supposedly began in the 80s when Zawahiri is said to have given medical treatment to Bin Laden in Afghanistan in the teeth of a Soviet attack. According to terrorism expert Bruce Hoffman, Bin Laden considered Zawahiri his mentor. Most experts believe 9/11 could not have happened without Zawahiri's controlling influence.
• This article was amended on 5 May 2011. The original referred to the murder by plutonium poisoning of Alexander Litvinenko in 2006. This has been corrected