One Direction was formed 11 years ago, propelling Niall Horan, 29, Zayn Malik, 28, Liam Payne, 27, Harry Styles, 27, and Louis Tomlinson, 27, to a stardom seldom seen since Beatlemania.
Formed on The X Factor by Simon Cowell, the five boys did not know each other but were thrown together with little experience or preparation for what would follow.
"We had seen each other at Bootcamp and got on well, and Niall and I had shared a room," Liam would later recall.
"But we were competition then, and at the back of the minds we knew were against each other.
"So it was strange when we were put together and my first thought was, 'How are we going to make this work when we don't know each other?'
"It was such a leap of faith."
The risk paid off - they sold more than 70million records worldwide, becoming one of the best-selling boybands of all time, with a combined net worth of more than £280million today.
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Their dedicated fanbase were hysterical when in 2015, Zayn announced he was quitting the band, claiming he wanted to be a "normal 22-year-old" away from the spotlight, though he immediately embarked on his solo career.
The rest of the members confirmed they were going on indefinite hiatus months later, and have not reunited since.
Rumours had been swirling of rifts between the boys - and they have openly admitted that some were true.
By the time they scored their first number one with What Makes You Beautiful in September 2011, best mates Harry and Louis were renting a £3million flat in North London together.
But within a matter of months, they'd allegedly stopped talking and moved out amid talk of a mysterious feud.
"Apart from Harry and Louis, no one knows exactly what caused the falling out - they didn’t even tell the other boys the full details," a source told The Sun at the time.
"But it was very serious and their friendship has never recovered."
Feelings were apparently so frosty that the boys refused to travel together and bosses had to find a way to make the last three albums without the band being in the studio - claims Louis denied.
Even Niall dismissed the reports, telling fans not to believe the rumours.
"We stand strong as a band and we’re brothers," he tweeted.
But their bandmate Zayn revealed that the 'Larry Stylinson' fan fiction - which depicted the pair as lovers - had caused the boys to pull back from the friendship.
In an attempt to make fans understand the impact of their comments, Zayn told The Fader: "It’s not funny, and it still continues to be quite hard for them.
"They won’t naturally go put their arm around each other because they’re conscious of this thing that’s going on, which is not even true.
"They won’t do that natural behaviour."
For Louis, he took issue with the impact the gossip was having on his own relationship with then-girlfriend Eleanor Calder, and admitted the speculation had 'created an atmosphere' between him and Harry.
"When it first came around I was with Eleanor, and it actually felt a little bit disrespectful to Eleanor, who is my girlfriend now.
"I’m so protective over things like that, about the people I love," he told The Sun.
"It created this atmosphere between the two of us where everyone was looking into everything we did, it took away the vibe you get off anyone.
"It made everything, I think on both fences, a little bit more unapproachable."
While Harry has refused to put a label on his sexuality, Louis identifies as heterosexual and was furious when a cartoon featured in HBO show Euphoria depicted a sex scene between him and Harry last year.
"I can categorically say that I was not contacted nor did I approve it," he raged on Twitter, with a source telling The Sun he was '"angered" that an "awkward" situation had been made worse.
Despite the drama, Louis and Harry still seem to be friends, with the latter joining Niall and Liam to support Louis' emotional X Factor performance following the death of his mum, Johannah Deakin, in December 2016.
Meanwhile, Louis and Liam also clashed during their time on The X Factor.
"We used to be at each other’s throats," Louis admitted on their This Is Us DVD.
"Whenever I wanted to do anything slightly mischievous, he was always the daddy."
"Me and Louis did not get on at all," Wolverhampton-born Liam agreed.
"We were two completely different characters, there was one point where I literally wanted to whack him."
And Liam recently admitted he felt relief when the band finally split up.
"The day the band ended, I was like, 'Thank the Lord'," he told The Diary of a CEO Podcast.
"I know a lot of people are going to be mad at me for saying that, but I needed to stop or it would kill me."
He explained that he drank heavily to see him through the "isolation" of constant touring and the pressures of fame.
"In the band... The best way to secure us, because of how big we’d got, was just to lock us in our rooms," he said.
"What’s in the room? A mini-bar.
"So, at a certain point I thought, I’m just going to have a party-for-one and that seemed to carry on for many years of my life."
Liam added: "Then you look back at how long you’ve been drinking and you’re like, 'Jesus Christ, that’s a long time.'"
He added: "It was wild, but it was the only way you could get the frustration out."
Liam, who said he has now been sober for a month, added: "Don’t get me wrong, we had the best time ever, but... You don’t realise you have a choice at that point."
All five members have gone on to have hugely successful music careers, and some have even become fathers.
Liam welcomed Bear, four, with ex-girlfriend Cheryl, while Louis shares son Freddie Reign, five, with ex Briana Jungwirth.
In September last year, Zayn's girlfriend Gigi Hadid gave birth to their daughter Kai.
Meanwhile Harry is rumoured to be dating US actress Olivia Wilde, and Niall is dating fashion buyer Amelia Woolley.
In 2020, Liam let slip that while he, Harry, Louis and Niall got in touch to discuss their ten-year milestone, he had ruled Zayn out of any possible reunion.
"I don’t think that’ll ever happen," he told the Jonathan Ross show.
"When [Zayn] left, it wasn’t on great terms so I don’t feel like it’s a thing. If he didn’t want to be here, he shouldn’t be here, which is fine."
But Simon is convinced he can persuade the five to reform – as soon as he can get them all in a room together.
He recently said: "I think it will happen.
"If they got together, whether it’s making records again or touring, it would be the most amazing thing."
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