Bobby Jarzombek (Spastic Ink, Halford, Riot)
Nobody can touch Bobby, IMO. Insane chops, great feel, impeccable timing. He is the god of drumming.
Sean Reinert (Cynic, Death, Aghora, Gordian Knot)
One of the first, if not THE first, to mix jazz drumming into metal. Was a long time favorite until I heard Bobby.
Tim Alexander (Primus, Attention Deficit, Oxygene8)
I never fully appreciated him until I heard Attention Deficit. I'm paying attention now.
Brann Dailor (Mastodon, Lethargy, Today is the Day)
Just a monster. He's all over the kit, yet it all works together somehow. The dude must sweat gallons during a show, he nevers stops moving.
Asgeir Mickelson (Spiral Architect, lots of black metal bands)
Easily the best thing to come out of the Norwegian BM scene. Hellhammer Schmellhammer. Asgeir is so much better. All Hellhammer has is speed; Asgeir has it all.
Dave Lombardo (Slayer, Testament, Grip Inc.)
Definitely one of the best metal drummers around. He may not have the jazz timing that some of my other favorites do, but for thrash, look no further.
Neil Peart (Rush)
From my understanding, he was the first to use 32nd notes in drumming. Of course, I was like 14 when I heard that, so it probably isn't true. Still, he's a legend you have to respect.
Bill Bruford (Yes, King Crimson, Gordian Knot)
I don't think he's quite as good as some people make him out, but he's definitely worthy of his legend status.
Alex Arellano (Power of Omens)
He does some very unqiue things with his drums. It's all in the timing, too. Gotta respect him, even if it is a bit much for the music.
I wish I knew the names, but the following bands have insane drummers, too:
The Mars Volta
Ephel Duath
Nebelnest
Sotos