I think you would need to define influential, as in, in what way?
The Beatles spawned an entire genre known as the British Invasion which was a direct result of the reception of their music in the states. So in terms of influencing a particular movement in rock they certainly played their part. And of course, much of their music was pretty innovative and original.
Elvis Presley, influenced an entire generation of music, opening the door to rock as a genre.
Many would claim that Jimi opened the door to the hard blues rock that serves as the foundation for so much music, even today. But he wasn't the originator of that style of playing. Jimi's influences included Muddy Waters who really developed the electric blues style, Jimi just sort of took it to the next level. But in that case, who was the real influence on the genre? The guy people most commonly credit, or the guy who influenced that guy? And I'm just going to say it: Jimi was really not a great guitar player. Much of his playing was pretty sloppy and a lot of sour notes (maybe a byproduct of his excessive drug use, but we'll never know for sure) . What he was, was fast, which in many people's eyes made up for his lack of accuracy.
Furgal mentioned Eddie VanHalen, and I have to admit, I think he did sort of reintroduce the guitar and made a lot of old time guitar players question themselves. He was certainly innovative in his playing, but the music wasn't new at all. It became even more mundane and typical when Sammy Hagar joined the group. So imo VanHalen's only real contribution was in the realm of guitar technique, but he wasn't the first, or the last. Jeff Beck, Robin Trower, Adrian Belew, and Leslie West were making their guitars do unbelievable things before Eddie hit the scenes. Eddie just appealed to a larger audience because the music was so generally mainstream. Players like Joe Satriani, Steve Vai (who learned from Joe) have continued to push the boundaries of guitar sounds.
Then you have bands like Emerson lake and Palmer who were essential in the prog rock scene along with Yes, Gentle Giant, Genesis, etc.
I could go on and on....
Good topic though.
[This message has been edited by Taijiguy (edited 06-29-2015).]