Some biographers have actually argued that George Martin was properly the third Beatle, based on his critical song contributions.

And… you know what? That’s actually quite a strong argument as I personally see it. I mean, Sir George wasn’t just the one who discovered them in the studio sense, but he really did help morph their music over the years, as well as contribute an utter, direct landslide of musical creativity to their songs, things which are well and highly-documented across a load of sources & histories.

That said, for my part, Brian Epstein was an absolute boss. I don’t see how he’s outside the core.