AN ISIS "matchmaker mum", mass executioner and "Jihadi Jack" are reportedly among 150 terrorists who could return to the UK after Shamima Begum's bombshell ruling today.
The 20-year-old jihadi bride is now able to come back home to try and get her revoked British citizenship back.
And the shocking ruling has opened the door to return for dozens of other Brits who fled the country to join the terror group.
Dr Alan Mendoza, executive director of the Henry Jackson Society, said:
“The deeply troubling implication of this judgement is that up to 150 terrorists are now legally entitled to enter the UK in order to appeal the decision in their case.
"This decision could have dramatic repercussions for our entire counter-terror strategy.”
At least 900 went to join ISIS in Syria and Iraq during the caliphate's reign of terror, and while hundreds have come home, there are still many in Syria.
Today's Court of Appeal ruling comes as a "bitter blow" for the government who revoked her citizenship last year. Sources have slammed the decision to allow her back, which could see other terror sympathisers return to the UK.
Following the ruling a Home Office spokesperson said: “This is a very disappointing decision by the Court. We will now apply for permission to appeal this judgement, and to stay its effects pending any onward appeal."
Terrorism expert Dr Paul Stott told Sun Online returning fighters can pose a serious threat to UK security "because they have military training [and] combat experience"
"The UK has taken back some former fighters, and there have been a few successful prosecutions. We have also – correctly – looked to block dual nationals from returning by cancelling their British citizenship.
"But that still leaves potentially several dozen Britons, in Kurdish custody, who can’t stay there for ever. It is not at all clear what happens next."
The AK-47-toting 'ISIS matchmaker'
Brit mum Tooba Gondal is a former AK-47-toting ISIS bride who groomed jihadi brides, taunted UK cops on social media, and bragged about living a life of "real freedom".
She is even rumoured to have recruited Shamima Begum into the Islamic State.
The daughter of a successful businessman, Gondal previously enjoyed a western lifestyle - including clubbing - but fled her east London home to join ISIS in 2015 aged 22.
Dubbed the "ISIS matchmaker", Gondal used to be married to a key Islamic State recruiter, Abu Abbas Al-Lubnani, who offered cash incentives to teen girls via a UK-based cell.
Al-Lubnani was killed in fighting in August 2015.
Now aged 25, Gondal is reported to be living in Ayn Issa camp with her two young kids following a failed escape bid from then-ISIS-held Baghouz village to the Turkish border.
"I want to face justice in a British court," she moaned. "I wish to redeem myself. I would like Britain to accept my apology and to give me another chance."
The bouncy castle salesman-turned-executioner
Former bouncy castle salesman Siddhartha Dhar, 36, is an ISIS executioner who was filmed leading the barbaric killing of five shackled men accused of being spies for the UK.
He was even seen threatening then-prime minister David Cameron - whom he called an “imbecile” before shooting a prisoner in the back of the head in cold blood.
Dhar, from Walthamstow, east London, converted to Islam in his teens and was lured into extremism by hate preacher Anjem Choudary's banned Al-Muhajiroun group.
He renamed himself Abu Rumaysah, openly defended ISIS and in 2014, managed to flee undetected by coach to Paris and on to Syria with his pregnant wife and four kids.
Once in Syria, Dhar, dubbed "Jihadi Sid", was pictured brandishing a rifle and accused of sickening crimes - including kidnapping a Yazidi refugee and raping others.
Despite earlier rumours that Dhar was killed in a drone strike, these have not been confirmed - and may even have been spread by the terrorist himself.
Dr Stott explains: "It was never going to be easy for him to slip under the radar of the authorities.
"It is possible he sought to use that fame to his advantage, by getting associates to spread rumours he had died, potentially allowing him to leave Syria for another combat zone."
In similar cases, 'missing' or 'dead' jihadis have been tracked down in refugee camps and prisons.
Farmer's son Jack Letts, 24 - who holds dual Canadian citizenship through his father - infamously declared himself an "enemy of Britain" after fleeing to fight with the terror group in Syria.
After being captured, he pleaded to be allowed back to his Oxfordshire home saying he had "no intention of blowing up Britons."
Letts - currently being held in a Kurdish jail - fled to Syria in 2014 aged 18, having converted to Islam two years earlier.
In Syria, he reportedly changed his name to Abu Mohammed and married an Iraqi woman with whom he has a son, Muhammed.
Last year the British Government stripped him of his citizenship.
The ISIS gravedigger and his jihadi wife
Dad-of-five Shahan Choudhury, 32, from London, is an ISIS gravedigger who buried scores of bloodied dead bodies as the Syrian town of Baghouz became a "slaughterhouse".
A former suspect in a gang murder, Choudhury vanished from his flat overnight in 2014 and headed to Syria - because, he claims, he was simply "curious" about ISIS.
He was later joined by his wife and their young children. It has been reported that the family may have used housing benefit payments to fund their journey.
Once in Syria, Choudhury is accused of using social media to urge other British Muslims to carry out terror attacks in the UK and became an Islamic State gravedigger.
Now caged in a secret Syrian prison for male ISIS fighters, he recently told ITV: "Somebody has to bury the dead people, who’s going to do that? There were dead bodies everywhere."
He added that Baghouz "was a complete slaughterhouse" in ISIS's final days.
Despite claiming that he didn't actually fight for the terror group, Choudhury, now 32, didn't reveal what he'd been doing before he took on his grisly gravedigger role.
But he did say he'd made a "mistake" by coming to Syria.
"I don’t think I have any future... most probably I'll be in prison for the rest of my life so I don’t have any hope," he said, seemingly resigned to never returning to Britain.
Fast food-loving jihadi dubbed "Hungry Hamza"
Fast food-loving jihadi Hamza Parvez, 25, has appeared in ISIS propaganda videos, encouraged others to join the death cult, and once hailed the "golden era of jihad".
Dubbed "Hungry Hamza", he was teased by fellow jihadis for his bulging waistline - and whined about missing KFC and Nandos while in Syria.
Parvez, originally from north west London, joined ISIS aged 20 in 2014 - around the time the terror group seized Fallujah, in Iraq, and Raqqa, in Syria, at the height of its power.
He soon became known for his bizarre online posts, including one of him eating ice cream in Mosul. In another, he declared the UK was "not the land for us."
In an exclusive interview with Sun Online last week, he claimed he himself worked as security for mosques in Baghouz, where many people were slaughtered and forced into sexual slavery.
He also said he felt no guilt over his role in the group's deadly reign of terror.
"I would have guilt [for joining ISIS] if I had personally committed a crime, by my own actions, by my own tongue, from my actions,"the former police cadet said.
"I don't think I can [be] judged by my own actions."
The schoolgirl who fled with Shamima Begum
Schoolgirl Amira Abase fled from Bethnal Green, east London, to Syria in February 2015, along with notorious ISIS bride Begum and their pal Kadiza Sultana.
Her whereabouts remains a mystery, though there were reports she may have been killed in an airstrike.
Abase's dad, Abase Hussen, declared that his daughter and Begum, who was then heavily pregnant, should be allowed to come home because they pose "no threat".
But the Home Secretary told The Sun on Sunday: "Our job is to keep our country safe."
“We cannot have people who would do us harm allowed to enter our country – and that includes this woman," she added.
The ice cream salesman "willing to die for ISIS"
Aseel Muthana went from an ice cream salesman in Wales to an ISIS supporter in Syria, where he is said to have become a prolific recruiter for the terror group.
Aseel was tracked down to a hellhole prison in northern Syria by ITV News - where he is packed in with thousands of men and boys.
Now aged 22, he says he misses his mother Umm Amin and wants to return home.
In a message to his mum, he urged her to "try to stay strong", adding: "What’s happened has happened and we both believe in Allah and we believe that Allah will make a way out."
Aseel - who was one of the first British recruits to join ISIS - claimed he initially thought he would be helping poverty-stricken Syrians by fighting on their behalf when he fled to Syria.
He described his move overseas as being "before all of these beheading videos".
She urged Britain to bring him back. "My little boy went seduced [by ISIS] and brainwashed with ideas that were not his," she claimed.
The "skilled" bomber
Aseel's brother Nasser taught his younger brother about jihad and featured heavily in an ISIS recruitment video.
Once a promising medical student, Nasser left Cardiff for Syria in 2013 and rose to become one of the UK's most high-profile - and boastful - ISIS fighters.
He previously posted a photo online showing a stash of homemade bombs.
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Now in his mid-20s, he is among the UK's most wanted and has even been subjected to United Nations sanctions, involving a travel ban and the freezing of his assets.
He's previously been rumoured to be dead following an air strike.
But if, like his brother, Nasser ends up being discovered alive, languishing in a Syrian prison, he and his terrifying "skills" could end up being brought back to Britain.