I must preface my statement by saying that I made a mistake. I consider "Rock 'n Roll" to be stuff like Elvis, and that kind of thing that was popular in the 50's and early 60's. Rock, on the other hand, is music like Zep, or GnR, although I don't think AC/DC or GnR were metal, that's a bit of a stretch. So by this definition, the Beatles could have been Rock 'n Roll however I still classify them as 60's pop music. Although you could argue that, by definition, Pop Music is what is popular at the current time and at that time Rock 'n Roll was the Pop music but eh. Whatever.
I still personally don't classify the Beatles as straight up Rock or Rock 'n Roll, although I do agree that they contributed greatly to music as a whole, as @John_Smith said.
Also on the topic of great bands of the 60s. The Jimi Hendrix Experience, of course. =P Jimi didn't headline Woodstock for nothing.