THE title of the "Fifth Beatle" is often thrown around, but there was only one man who truly earned the honour.
In a year when so many music legends have passed away, the death of Beatles producer Sir George Martin closes another chapter in the band's history.
Without him, I wonder whether The Beatles would have progressed from their early rock'n'roll phase to create some of the most iconic music of the 1960s.
Indeed, the "mop-tops" as we know them wouldn't have existed were it not for Martin's suggestion Ringo Starr replace original drummer Pete Best after their initial recording trial at Abbey Road.
A father figure to the boys, Martin guided the band through their biggest hits.
In a statement, Paul McCartney paid tribute to "the most generous, intelligent and musical person I've ever had the pleasure to know".
It was Martin who suggested a string quartet be added to McCartney's first solo Beatles recording, Yesterday.
He also oversaw the string arrangements which gave Eleanor Rigby a haunting, melancholic beauty.
As The Beatles became more involved in psychedelic culture, Martin's technical expertise allowed their creativity to blossom.
Together they pushed the boundaries of modern music with songs like Strawberry Fields Forever and A Day in the Life.
When the band was at breaking point and relationships within the group at their lowest, Martin pulled them together to produce their final tour de force, Abbey Road.
The music of The Beatles has formed the soundtrack of my life and the lives of millions of others.
It's sad to see such an important and iconic figure in the music industry pass away, but he leaves a lasting legacy.
As The Beatles once sang, "and in the end, the love you take, is equal to the love you make".