David Mazzucchelli. He broke into the comics industry thanks to writer Jim Krueger, whom he met at Megacon in Orlando, FL (while still in high school).
Rivera's best known painted work is Mythos, a series of six richly-painted origin stories written by Paul Jenkins. Originally published as one-shots, it was collected into a hardcover edition in 2008. He now limits his painted work to covers including The Twelve, The Iliad, The Amazing Spider-Man, and Wolverine, among many others. Most recently, he penciled 6 issues of Mark Waid’s Daredevil run. His father, Joe Rivera, inked the issues, for which they received 2 Eisners.
You can see Rivera’s art and take an in-depth look at his creative process at The Self-Absorbing Man, a blog that he updates regularly. His original art can be found at Splash Page Comic Art.