The Beatles were fortunate to be paired with George Martin, I think.
He has/had an incredible combination of talents, and played a number of roles to them. He would be the father figure when they needed discipline, support, encouragement, even telling off at times. But at the same time, he was blessed with the imagination and energy to help turn The Beatles' ambitions for their music into reality.
Fact: Lennon once asked George Martin to make one of his songs "sound like an orange".