Max Martin wrote all your favourite songs, and you've never heard of him.

If you’ve ever snorted disdainfully that “all the music on the radio sounds the same”, there’s a very good reason for that.

It’s likely that at some point, you’ve danced to Taylor Swift’s “Shake It Off“.

Perhaps you’re a diehard Swift fan, or perhaps the catchy tune just caught you off guard: either way, it’s hard to deny that pop music’s It Girl struck gold with 1989, an album that has even the most devoted alternative music fans tapping their feet.

Swift’s self-penned first, second and third studio albums were well-received, but despite growing popularity, Swift did not break the coveted number one spot on the Billboard Hot 100 Chart.

Before she released her fourth album, her recording studio made a controversial suggestion: that Swift, for whom writing her own music was a point of pride, collaborate with an established songwriter in a bid to crack number one.

As soon as this collaboration was in place, the album’s first single, “We Are Never Ever Getting Back Together”, reached number one only a week after its release.

Taylor’s self-written songs weren’t breaking through. But her most popular tracks were all co-written by notoriously withdrawn Swedish music producer and writer Max Martin – including the stand-out anthem, “Shake it Off”.

Surprised? You’re not the only one. But with his songs launching the career of Britney Spears (he wrote, ‘Hit Me Baby (One More Time)’ and ‘Oops, I Did It Again’), Katy Perry, P!nk and Kelly Clarkson, Martin’s legacy is almost as unknown as it is vast.

Born Karl Sandberg, Martin began his career working with Swedish and European pop acts. He broke into the American music scene when he co-wrote four songs on the Backstreet Boys’ debut album, The Backstreet Boys – but only truly gained recognition in the industry for his work on the Backstreet Boys’ third album, Millennium. (Once you’ve written a song as universally beloved as “I Want It That Way”, it seems there’s no going back).

Martin has since co-written 20 number one songs, making him the third most successful song writer of all time behind Paul McCartney and John Lennon. Indeed, McCartney and Lennon better watch their backs – Martin is producing hits at an alarming rate, with no suggestion of slowing down.

If you’ve ever snorted disdainfully that “all the music on the radio sounds the same”, you’re not far from wrong: a good chunk of it bears Martin’s signature. Katy Perry, Taylor Swift, Britney Spears, P!nk, Kelly Clarkson, Taio Cruz, Ariana Grande and Justin Bieber all collaborate, or have collaborated, with Martin on one or more of their top-ten songs. And it’s not just pop – he’s written best-seller for Bon Jovi too.

Yet Martin himself remains almost entirely unknown outside the music industry. Part of that has to do with his own cultivation of a scrupulously private persona, never granting interviews and rarely appearing in public in a professional capacity. The musicians Martin works with can hardly be accused of hiding their collaboration with him – credit is scrupulously given where credit is due – which only makes Martin’s anonymity all the more startling.

A look back at Martin’s catalogue of hits reveals the extent of his influence on the musical tastes of our generation. He penned Britney Spears’ iconic hit “Oops I Did It Again”, as well as “… Baby One More Time” and the more recent “Hold It Against Me” and “3”.

He cemented Kelly Clarkson’s transition from American Idol winner to bona fide pop star with “Since U Been Gone” and “My Life Would Suck Without You”.

He co-wrote every Katy Perry song you know: “Teenage Dream”, “I Kissed A Girl”, “Last Friday Night”, “E.T”, “Part Of Me”, “Roar”, “Dark Horse” and “California Gurls”.  Recently, he had hits with Ariana Grande’s “Problem”, Justin Bieber’s “Beauty and a Beat”, and the Weeknd’s “Can’t Feel My Face”. His back catalogue features the Backstreet Boys’ “I Want It That Way”, Bon Jovi’s “It’s My Life”, *NSYNC’s “It’s Gonna Be Me” and P!nk’s “So What”.

Closer to home, Martin was responsible for The Veronicas’ debut single “4ever”.

If that reads like a history of pop music over the last two decades, it should – Martin has been influential in shaping pop music as we know it.

It’s unfortunate that nobody remembers his name.