Alexanda Kotey, who along with friends Aine Davis and Mohammed Emwazi, left west London to travel for Syria to join Isis.
After joining the militant group, they became known by the hostages they guarded as 'The Beatles' - with Kotey, Davis and Emwazi given the nicknames George, Ringo and John.
But they were just a small part of a wider network of British men believed to have been radicalised by Kotey.
Here is what ITV News understands about Kotey’s friendship group from west London who became some of the most notorious terrorists in the world.
Kotey, 34, became a key IS recruiter after converting to Islam in his twenties.
The father-of-two, born into the Greek Orthodox Church, went on to lead the so-called 'Beatles' cell in Syria, which held hostages and executed a string of western captives including Britons David Haines and Alan Henning.
It is believed Kotey was responsible for radicalising a several young men in west London before leaving Britain.
He was arrested by Syrian Kurdish forces earlier this year, and will now face trial, probably in the United States or UK.
The son of a Saudi diplomat, Hassane, who grew up in London, was a direct associate of Kotey and Davis in London before the pair left for Syria.
The 24 year-old, who was studying medicine in Sudan until his arrest in 2014, admitted being the ringleader of a major IS-inspired plot to spread terror on the streets of London.
Detectives suspect he had also travelled to Syria.
El Shafee Elsheikh
A British citizen whose family fled Sudan in the 1990s, El Shafee Elsheikh was arrested alongside Kotey.
American officials say Elsheikh, known to friends as ‘Shaf’, travelled to Syria in 2012, first joining Al-Qaida’s (AQ) branch in Syria, and later joined ISIS. While in Raqqa he is thought to have become a member of the terror cell known as ‘The Beatles’.
For months Islamic State's infamous front man, Emwazi became known around the world as 'Jihadi John' after executing western hostages including Britons David Haines and Alan Henning.
He was part of the west London crew who became radicalised on the streets around Ladbroke Grove before fleeing to Syria.
Unmasked in February 2016 as another member of the so-called 'Beatles' cell, Davis, 34, is a former drug-dealer who was jailed for terror offences in Turkey after leaving Syria.
He left Britain in 2013 and joined IS, where he helped detain and murder western hostages alongside Emwazi, Elsheikh and Kotey in the IS stronghold of Raqqa.
His wife, Amal el-Wahabi, was jailed in 2014 for funding terrorism.
An alleged al-Qaida member from London who was killed in a US drone strike while fighting alongside Islamist insurgents in Somalia.
Berjawi, from St John’s Wood, is thought to have first travelled to Mogadishu in 2007 before making several subsequent trips to the country, eventually operating at a senior level within al-Shabab.
The west Londoner prayed alongside Alexanda Kotey as a youngster. He said he travelled to Syria to fight against the Assad regime.
State television reported in 2013 that Almanasfi had been killed in an ambush in Idlib. Since then, evidence has emerged to indicate he is still alive in Syria.
The body-building former Holland Park student was also known as Abu Musa al-Britani.
Older brother of Fatlum Shalaku, the 23-year-old architecture student was also known as Abu Saeed before he was killed on the frontline in March last year.
The engineering student is believed to have been radicalised by Alexanda Kotey in west London before travelling to fight in Syria.
The 23-year-old from Ladbroke Grove, west London, was the second British fighter to be killed as he fought Assad’s forces in 2013.
The 25-year-old, who worked at a hotel in Shepherd's Bush, is believed to have married in Syria and is still fighting with the jihadists.
A former school pupil in Holland Park, west London, who died in Syria after leaving his undergraduate business course to join the conflict.
He was killed in June 2014 after being hit by shrapnel.
The Londoner, who was of Moroccan origin, got into petty crime at home before travelling to Syria, where he died in Aleppo in August 2013.
The 25-year-old grew up in the streets of west London. He became one of the first Britons to die in Syria - killed in a fire fight in 2012.