Although his nearly singleminded fixation on sex has been a constant plumb line, R. Kelly's catalog is remarkably diverse. Stylistically, over the course of a 20-year solo career he's evolved with the times from New Jack Swing all the way to the Auto-Tune era and beyond, to the point that his latest album features a Future collaboration that could pass for Drake. Conceptually, too, the guy has covered a lot of ground; in recent years he's delivered two straightforward traditionalist soul albums and dozens of bonkers Trapped In The Closet chapters. Kellz once released a double album with one disc full of steppin' music and another dedicated to gospel songs. He's done duets with everyone from Celine Dion to Jay-Z. His discography includes both the all-time classic inspirational ballad "I Believe I Can Fly" and "Real Talk," a maniacally funny, progressively agitated one-sided phone call as R&B slow jam (and still my favorite R. Kelly song on most days, although "I'm A Flirt [Remix]" is stiff competition). And perhaps even more than R. Kelly has stayed in step with the times, the times have stayed in step with R. Kelly. He's a pioneer of explicitness, continuously pushing the boundaries of how openly freaky pop music can be. His influence on urban music is widespread and unmistakable, from the radio dominance of Trey Songz to the underground sexcapades of Ty Dolla $ign. Kellz was born with a voice that can conjure the elemental life forces that hold this universe together, and he's used it to do just about everything an R&B singer can do.