Right now, Jack Antonoff is perhaps the most successful man in the music industry.
Not only is the 40-year-old producer credited on 16 tracks on Taylor Swift's latest release The Tortured Poets Department - but he can also be found on the credits of works by Lorde, Lana Del Ray and Florence and The Machine.
And the producer's love life is just as star-studded as his job. Jack has dated Scarlett Johansson and Lena Dunham - and he is now married to Andie MacDowell's daughter, Margaret Qualley.
Despite his extraordinary success (and being beloved by Swifties around the globe), Jack is still relatively unknown considering just how key he has been in creating some of the greatest albums of the last few years.
He's also an award-winning musician in his own right, having been a part of bands Steel Train and Fun - and now being the frontman of Bleachers.
As Taylor releases her 11th album, FEMAIL looks at the man behind some of music's current biggest stars...
Dream team: Considering how instrumental he's been in Taylor Swift's recent career, Jack Antonoff is still surprisingly unknown. Pictured after winning Album Of The Year for Folklore in 2021
Taylor Swift's 'co-pilot': How close friend Jack Antonoff has been behind some of her greatest hits
Jack and Taylor first met in 2012 at the MTV Europe Music Awards. Their first official collaboration was not one of Taylor's best known hits (but nevertheless is still an absolute tune): Sweeter Than Fiction from the One Chance soundtrack.
They collaborated properly for the first time on 1989, producing Out Of The Woods (the sixth single from the album), I Wish You Would, and You Are In Love.
1989 won Album Of The Year at the Grammys - an accolade which Taylor has now won three times.
Taylor told the New York Times in 2017: 'Sometimes he sits at the piano and we both just start ad-libbing and the song seems to create itself.
As well as being her producer, Jack is also one of Taylor's closest friends
Jack and Taylor were pictured deep in conversation at this year's Grammys - moments before she surprised the world by announcing the release of The Tortured Poets Department
'His excitement and exuberance about writing songs is contagious. He's an absolute joy. That's why everyone loves him. I personally wouldn't trust anyone who didn't.'
She worked with Antonoff again on subsequent albums Reputation and Lover. A video of the two creating Getaway Car from Reputation is particularly adored by Swifties.
On Folklore (2020), Taylor began collaborating with The National's Aaron Dessner too - but Antonoff still had a clear part to play and starred in documentary Folklore: The Long Pong Studio Sessions, which was released in November 2020 about the making of the album.
After winning Album of The Year at the Grammys again for Folklore, Antonoff wrote on Instagram: 'And @taylorswift, from 1989 to here … goddamn. you are the one who let me produce records first.
'Before you, Ijust ‘wasn’t a producer’ according to the herbs. Ijust wasn't let in that room. Then I met you, we made Out of the Woods and you said, "that’s the version" and that changed my life right there.'
He has also featured as a producer on the re-recorded versions of her albums - Fearless, Speak Now, Red and 1989.
Jack and Taylor first met in 2012 - and he has been key in collaborating with the global star ever since, and says she changed his life by giving him a chance to produce on Out of the Woods
When Taylor released the album Midnights in 2022, she said Jack was her 'co-pilot'; his production featured on every track
She also called him a 'friend for life' - and the two are clearly very close, spending a lot of time together outside of rehearsals
The album Midnights, released in October 2022, featured his production on every track for the first time - with Taylor even calling him her 'co-pilot'.
'Midnights is a wild ride of an album and I couldn’t be happier that my co-pilot on this adventure was @jackantonoff,' Swift wrote via Instagram after the album’s release.
She also called him a 'friend for life' - and the two are clearly very close, spending a lot of time together outside of rehearsals - while she has also brought him on stage to perform with her during her Eras tour.
He came to her defence in February 2022 after blur frontman Damon Albarn claimed she doesn't write her own songs and is fiercely protective over her songcraft - even hanging up on an interview when quizzed about his involvement in The Tortured Poets before it was released.
When album was finally released on Friday, Antonoff said 'Love this album more than I can say... Love you all very much... more later very overwhelmed... love you Taylor.'
Ever since Folklore, Taylor has also collaborated with the National's Aaron Dessner
A star-studded love life too: High profile exes and a famous wife
Jack attended the same high school as Hollywood actress Scarlett Johannsen and the pair reportedly dated for a year and went to prom together. The romance - thought to take place between 2001 and 2002 - is said to have fizzled out after they graduated.
He then dated Girls actress and creator Lena Dunham from 2012 to December 2017.
Taylor has admitted that You Are In Love - which was produced by Jack on her 1989 album - is about Dunham.
The producer married Margaret Qualley, 29, in a New Jersey wedding in August 2023, attended by Swift, who reportedly gave a 15 minute toast to the newlyweds at the nuptials.
Jack was first romantically linked to the Maid actress, who is the daughter of Four Weddings and a Funeral actress Andie MacDowell, in August 2021.
Jack attended the same high school as Scarlett Johannsen and the pair reportedly dated for a year and went to prom together. Pictured in September 2002
In 2012, he started dating Lena Dunham (pictured in 2017), whom he was with for five years until they split
Love match: Jack married to Margaret Qualley, 29, in a New Jersey wedding in August 2023
Margaret is the star of Netflix's Maid and is the daughter of Four Weddings and a Funeral actress Andie MacDowell
Collaborations with other artists: How Antonoff has produced Lorde, Lana Del Rey and Florence and The Machine
Though he is now best known for his partnership with Taylor, Jack also works with the likes of Lorde, St Vincent, Lana Del Rey, The Chicks and Florence and The Machine.
Jack worked with Lorde on her second studio album, Melodrama, which came out in 2017, and her third album Solar Power, which dropped in 2021. He co-wrote and produced both LPs.
He also appeared in the music video for the lead single, Green Light, and performed the song Liability alongside Lorde on Saturday Night Light.
'Much has been said of Jack’s ability to be an empathetic, sensitive and respectful collaborator to women, and while that’s certainly true, I’d put his success down to another of his more underrated qualities: how fast he is,' Lorde told Billboard.
Jack worked with Lorde on her second studio album, Melodrama, which came out in 2017
Jack was also a co-producer on Lana Del Rey's sixth album, Norman F***ing Rockwell!
'I’ve never heard anyone beat up the keyboard like Jack making a beat in 30 seconds on Pro Tools.
'The dude can jump from instrument to instrument to build you a canvas upon which to write in minutes.
'It’s an invaluable creative tool for me, how easily he can pick up the thread and go wherever. When the two of us are racing to capture an idea, it’s like actual alchemy.
'We’re also just really close - he drives me crazy, pushes me to examine myself more carefully, and gives me s**t like no one else can. I’m team Jack forever.'
Jack was also a co-producer on Lana's sixth album, Norman F**king Rockwell!, in which he co-wrote a majority of the songs, as well as her seventh album, Chemtrails Over the Country Club and Did You Know That There's A Tunnel Under Ocean Blvd in 2023.
He also worked on the soundtrack for the romantic comedy Love, Simon, co-wrote Sara's hit single Brave in 2013, contributed to the production of P!nk's seventh album, Beautiful Trauma.
He produced eight tracks on Florence and The Machine's fifth studio album Dance Fever, released in 2022, including singles King and Free.
Lana Del Rey, Taylor Swift and Jack Antonoff attend the 66th annual Grammy Awards in February
Lana and Taylor collaborated for the song Snow On The Beach in Midnights, on which Jack's production featured in every song
Solo career: Steel Train, Fun and Bleachers
Taylor Swift's remarkable scoop of awards over the years might steal the headlines, but Jack Antonoff can also do front of stage.
He was previously in bands Outline and Steel Train and joined his pals Nate Ruess and Andrew Dost to form Fun in 2008 as guitarist and drummer.
Fun released famous hits Some Nights and We Are Young, which debuted on the Billboard Hot 100 at number one and won the Song of the Year award at the Grammys
Despite Fun's success, Jack recalled feeling like he wanted to do more. So in February 2014, he launched a solo project called Bleachers.
Jack is now the frontman of Bleachers, releasing his own music and performing at Coachella this year
After parting ways with Outline, Jack formed another band called Steel Train with friends, in which he was the lead singer. The band released two EPs and three full studio albums. He is pictured with the band in 2009
Fun's debut album, Aim and Ignite, came out in 2009, and its second LP, entitled Some Nights, dropped in 2012. The band is pictured on stage in 2013
'I remember immediately - immediately - feeling like, "I don’t want to play We Are Young when I’m 35." I don’t want to be defined by this,' he told the New York Times during a 2017 interview.
Jack started his own music festival, called Shadow of the City, in 2015. The one-day event takes place in Asbury Park, New Jersey, every year, and has seen a slew of famous performers like Hayley Kiyoko, Charli XCX, The 1975, Khalid, Carly Rae Jepsen, and of course, Bleachers.
Bleachers' self-titled fourth album was released on March 8 and Jack performed at this year's Coachella.