Where to start, really?
Pretty much inventing popular music as we know it, The Beatles had an utterly remarkable career arc - going from 'Love Me Do' to 'A Day In The Life' in just four years. Their albums quickly got more sophisticated as the 60s wore on. They started out with simple, fun beat-pop on Please, Please Me and With The Beatles. A brilliant mid-career patch saw records like Rubber Soul and, particularly, Revolver. The way cleared to do pretty much whatever they wanted, they released maybe the all-time classic 'concept' album - Sgt. Pepper's Lonely Hearts Club Band, which brought all kinds of hitherto unseen influences (Indian raga, music hall) into the pop realm.
Their self-titled 1968 album (also known simply as 'The White Album') invented the sprawling, overlong, but brilliant-if-you-shaved-a-few-bits-off double LP extravaganza (see also Fleetwood Mac's 'Tusk'). But from that point it was a case of slowly diminishing returns, and they finished with a bit of a whimper with the Phil-Spector-string-slathered Let It Be.
Rancour and ill-feeling prevented the band from ever reforming, but all four members (yes, even Ringo) went on to have successful solo careers - although once John Lennon was tragically shot in December 1980 those careers were already pretty much in the past. Yet they will live on - probably forever - as the most influential band to ever walk the earth, leaving behind a catalogue full of classics, standards, and sheer invention.