"Moonage Daydream" (David Bowie)

I marvel at David Bowie's genius.  In 1972, he created a character—a rock & roll alien that was one part Iggy Pop and one part Warhol Factory misfit—and turned it into a vehicle to bring his music to the masses.  Granted, things got complicated when the line between the character, Ziggy Stardust, and the real David Bowie began to blur.  But I still think the basic idea of being able to step into character and act as wild, creative, and unfettered as you want and then step out of character and go home at the end of the day is brilliant.
I also think the entire The Rise and Fall of Ziggy Stardust and the Spiders from Mars (1972) album is brilliantly executed—particularly the track "Moonage Daydream."  
The song actually was written by Bowie before the Ziggy concept ever took flight.  He recorded a version of it in 1971 for a short-lived side project called Arnold Corns, a "band" that basically consisted of Bowie and a fashion designer named Freddie Burretti.  The deal was, Bowie wrote and sang all of the words, and the meticulously dressed/coiffed Burretti played frontman and lip synced to Bowie's vocals.
Anyway, the Arnold Corns version failed to make any kind of commercial impact.  But it did plant the idea in Bowie's head of performing his songs as someone other than himself.
Also, it explains why "Moonage Daydream" doesn't really fit the narrative of Ziggy, unlike, say, the song "Starman" or the title track.  Nevertheless, it has that same brash and bold attitude that permeates the entire album.  And that vibe has as much to do with Bowie's delivery as it does with the guitar skills of the late Mick Ronson.
In fact, it's Ronson's guitar work that makes me love this song so much.  During the first half of the song, his playing is rhythmic yet melodic, punctuating Bowie's vocals perfectly.  During the last half of the song, when he launches into his extended solo, it's completely abstract and unhinged.  It wails and screams like the throngs of British teenagers who got glittered up and packed concert halls to catch a glimpse of The Spiders from Mars.  Apart from maybe John Coltrane's avant garde noodling on "My Favorite Things," I don't know of anything else on tape that sounds quite like it or that's packed with so much raw emotion.