Chicago (band)- “Mongonucleosis” LIVE 1977 not Rock so much as a Latin tune played (written) by a Rock Band. No matter, it’s a hoot!
The Beatles “Flying” from Magical Mystery Tour. Very short, but brilliant.
Sleepwalk was mentioned earlier–love that instrumental.
I guess this is mostly about official studio recordings. I could point to any number of live Grateful Dead jams, for example, but the studio versions of the tunes either have lyrics (which were occasionally omitted in concert), or aren’t very good, or were never recorded. Also, they’re usually segued into or out of other tunes, so maybe they’re not discrete performances to be considered (by the way, you people who are nominating instrumental passages within regular lyric songs are cheating).
“Pipeline” was mentioned, but not in the transcendent version by Dick Dale and Stevie Ray Vaughn.
17 Years - Ratatat.
It uses a spoken word sample in the beginning, but then it’s all instrumental. And it’s all rockin’.
Thanks for reminding me.
Also, I have to include The Audience is Listening by the immensely talented Steve Vai.
Flying In a Blue Dream by Joe Satriani
And a triple bill from Eric Johnson:
I actually love “Flying”, but didn’t mention it because it regularly shows up on people’s worst-Beatle-tune lists.
(I also like “Hot As Sun”, from McCartney’s first album.)
Yngwie’s early instrumentals are pretty damn good too. * Far Beyond The Sun, Evil Eye, Icarus Dream Suite Opus Whatever The Hell It Was,* etc.
And I think Vai’s best instrumental is For The Love Of God.
Agreed.
“La Villa Strangiato (An Exercise in Self-Indulgence)” by Rush (“Hemispheres” album)
One of my long-term goals is to learn how to play Texas Flood, though Stevie Ray Vaughan is more blues than rock.
On the other hand, nobody mentioned this for a reason, but I might as well toss in a Pepe little number called Popcorn. Trust me, it’s worth watching even if you never liked the original. (Which was not Kraftwerk.)
I don’t think there can be anything more ROCK like this:
Amazing.
Go back and check out Miserlou '95, Einstein. 
In addition to the previous Satriani tunes I would add