Alright, there's plenty of terrifying guitarists out their but here are my favourite, not necesarily the fastest but who gives a crap?
Joe Satriani ("Satch"), I much prefer him to his pupil Steve Vai even though Vai may be a better shredder, not too happy with the last album though.
Alex Lifeson (from Rush - check their late 70s/early 80s stuff, if you must buy only one of their albums get exit stage left)
Terje Rypdal (totally obscure norwegian guitarist plays jazz rock - his speciality is violining and he is extremely tasteful but is quite capable of a barbed wire shred. Try "if mountains could sing" This guy's tone is AWESOME. Has played with Ronnie Le Tekero from TNT - Norwegian rock band.
Kirk Hammett - Mettalica's guitarist, taught by satch.
Jorgensen/ray/donahue - scary threesome known as the Helecasters. All terrific viruosos with styles ranging from
virtuoso metal to slide and country, brilliant hybrid music,
I recomend new axes to grind but have only heard two of their albums.
Paco Di Lucia, John McGlaughlin and Al Di Meola - regularly play together on acoustics. All hugely talented in their own right. Paco=flamenco (**** hot fingerstyle), McGlaughlin and Al Di meola (Jazz/rock, jazz and classical styles depending on date and mood!)
Jon Pettrucci - Dream theaters axeman. Scary ****!