Some Guitarists

A Lion, is a cat, and so is a domestic tabby, but the two things are not the same.
A top end Superstrat is guitar
A vintage Gibson ES is a guitar
A Selmer, Gypsy Jazz, D-Hole is a guitar
A Segovia's Herman Hauser is a guitar
They all superficially appear to the be the same (they all have six strings and frets), but they are in fact completely different instruments.

A classical guitarist, is not an electric guitarist, is not a folk guitarist, is not a flamenco guitarist.
By my estimation, those are the major four groups of guitarists. Each is a separate art form, each has it's virtuoso's and it's ideal form. And like any art form the state of that art evolves. Even Classical guitar evolves, moves on, get's progressively better. But the Electric Guitar is perhaps the fastest evolving art, because the electric guitar is newest.

You might think that Andrés Segovia was the greatest guitarist ever to live. And that would be pretty hard to argue against Even in his 80's he was better than most. But Segovia never chalked a cross on the stage which represented the ideal spot to stand to get controllable feedback from a wall of Marshalls.
He never tried to make his guitar sound like a horse or an alien, by pinching a high harmonic and twanging the wang bar.
You might consider these arguments fascile but they're very real. The Electric Guitar (the sounds it makes, and the emotions those sounds evoke) is an art form, quite distinct from all the other guitar art forms
And You can try as hard as you like but you will never be able to play recognisable flamenco on a Les Paul. Nor are you likely to emulate Michael Hedges or Paco de Lucia on a Telecaster.

What makes guitars different (and therefore the styles of music played on them) is complicated. Quite obviously it is mainly to do with the strings used, and how the notes created resonate.
But, and I don't want to labour the point. You cannot really hope to be a virtuoso on both an Electric and a Nylon Strung Accounstic guitar. They are.. different instruments.

Now I don't want to get all 'chippy' and lefty about this, but 'the establishment' is quite 'reactionary'. By which I mean that the established order of things is slow to recognise the 'new', hostile to it usually.
So it is that when you go to your music teacher at school and tell him you want to learn how to play the electric guitar, they will smile at you and ask you why you wouldn't want to learn how to play Bach's Cantata's instead.
The Electric Guitar is an upstart. The instrument of upstarts, of the auto-didact working classes. It is a 'popular' instrument.
As such there are a lot of people who play the electric guitar, so there are a lot of people who aren't actually that good at it.
A lot of those people are also famous because of it, despite, not being very good at it.

And at that point (10,000 bad covers of Voodoo Child) the established world of 'music' throws out the baby with the bathwater. But I would like you to know that the Electric Guitar is not the poor relation of the guitar family, quite the opposite. There are virtuoso Electric guitarists, and they are every bit as good as a virtuoso flamenco player.

Now with that rant over, here are some people that for me have had the biggest impact on the art of Electric Guitar.

PS - If you think Slash should be in this list, you're on the wrong website. Look up and to the left and you'll find a 'back' button.