I think Jim Lee is one these artists that really doesn't need any presentations. If you already read some of the DC, Marvel or Wildstorm comics from the 80's to nowadays, you probably stumbled with some of his covers and pages. In my point of view, he's the best penciller that ever worked for these major companies, a truly master of his tools, always pushing further on style and concept.
You can see some more artworks form Jim Lee at his Comic Art Community Profile or at his DevianArt.
I'm a big fan of Green Lantern, since my girlfriend introduce me to Green Lanterns Corp Issue #1 I got in touch with the art of Patrick Gleason. Nowadays, Patrick have worked on other titles at DC comics as Batman, Robin, H-E-R-O, Aquaman, Brighest Day and JSA.
Esad Ribic is one of the most interesting comic book artist nowadays. Despite his work as a penciler, he's most known as a cover artist for Marvel comics. His ability to with composition, phisiology and colors it's what brought my attention.
You can see more from Esad at his Official Website.
Ron Salas is one my latest discovery on comic book art, his remarkable black and white style reminds me the masters Mike Mignolla and Frank Miller. Let's keep an eye on what this great talent will show us further on future, but for now let's check his latest illustrations.
You can check more from this skillfull comic book artist at his Official Website and at his Tumblr.