Melle Mel

Read somewhere that the Furious Five's "The Message" was crafted at the urging of a record exec for some socially conscious material, that Flash and the guys initially resisted for fear that their core audience wouldn't dig it. Whether that's true or not, when Melle Mel drops knowledge, the air crackles.
I had always liked "The Message" ever since hearing it twelve or so years ago, the soundtrack to my getting lost in the Bronx as a teenager in my '82 Accord at 2 in the morning. Even if he had done nothing else--and he's had plenty of sublime lyrical moments--I would rank Melle Mel as one of the most gifted rappers on the strength of that song.
More recently, though, I saw his performance in the penultimate scene of the much-maligned movie Beat Street, which for the record, you can promptly stop and eject right after Mel's exit, or else endure a Broadway-style modern dance/break dance-fusion fiasco. The verse he contributes is thematically similar to "The Message," but even more urgent in tone. And thanks to the big-studio film quality, Mel's peculiar body language is impossible not to read; hand by the side then thrust forward open and facing down, as if to quiet a jumping dog at his feet or bless a city from atop a mountain, face scrunched up like a man in anguish.

Note that on the youtube link, Grandmaster Melle Mel comes on after the other guy. Also notice the street footage in the first minute or so.

"The rise and fall, the last great empire,
the sound of the whole world caught on fire,
the ruthless struggle, the desperate gamble,
the game that left the whole world in shambles,
the cheats, the lies, the alibis,
and the foolish attempt to conquer the skies..."