@loomisjohnson beat me to The Byrds, but there's always The Everly Brothers (they broke big in the 50's, but also made great music in the 60's and beyond too), The Band (their first two albums came out in 1968 and '69), The Mamas & The Papas, Buffalo Springfield, Moby Grape, The Righteous Brothers, The Temptations, The Four Tops, The Drifters, The Platters, Dion & The Belmonts, and a little combo from Liverpool.