There are guitar gods and then there are people so convincing in the role that they are cast to play guitar gods on film. Steve Vai is both.
He has backed Frank Zappa and David Lee Roth, has his own custom model electric and acoustic guitars and pedals, and is an alumnus of the guitar virtuoso G3 tour organized by his old teacher, Joe Satriani. But if instrumental shred metal doesn't mean much to you, you still probably know Vai's work from film.
In the 1986 film Crossroads, Vai was cast as Jack Butler, the supernaturally talented devil who is challenged in a guitar showdown to win back an old bluesman's soul. The back-and-forth between Vai and The Karate Kid's Ralph Macchio one of the greatest climaxes in music-themed cinema.
And if you haven't seen that--a thousand pities on you--Vai is also the man behind the wicked air guitar licks in Bill and Ted's Excellent Adventure and Bill and Ted's Bogus Journey.