Looking for bloody dismemberment.

[Pikey Mikey]

Dead Space 2 or Gears of War 2 (the first games are just as bloody)
I could recommend Darksiders, but that game crushes your balls near the end by forcing you to do time consuming but unchallenging puzzles, just a heads up if you rent/buy/play it
Dead Rising 2 and God of War 3 I haven't played, but I played both the first DR and GoW, and the sequels are just as bloody or bloodier (Blood for the Blood God maybe?)
Bulletstorm is funny (a little to much swearing, but still) altough that is first person (but it works great)

 

[redpete17]

I had someone else mention the Myth series.
Also Diablo 3, if it is ever released.

 

[PlasmaFrog]

Madworld and the No More Heroes series are both charming, vulgar, and filled with cringing amounts of blood and gore.

Honestly, it's difficult to pass up these titles. Yet, if you're looking for something a little more advanced in the future, Metal Gear Rising promises loads of bloody fun.

 

[Dwarfman]

Fallout springs to mind. Even when it was an isometric look down game it had some pretty graphic deaths - specially when you took the bloody mess perk!

Planescape:Torment. The only game I know where your eye and intestines wind up in your inventory and you can use your severed arm as a club.

PLenty of people have already mentioned Mortal Kombat.

Dawn of War conatins decapitations, people being eaten, shot, blown up and incinerated.

 

[Trivun]

I'd say a few visual/sound novels. Higurashi no Naku Koro ni and Umineko no Naku Koro ni. They're pretty damn gory. Otherwise, though I hate these games and find these to be two of the very few games I would ban completely, I'd say Manhunt and its sequel.

 

[Moonlight Butterfly]

Yahtzee told me that in Dead Space 2 you can stomp on aliens using Ice skates (lol)...just sayin.

 

[Saelune]

God of War

This is exactly what you're looking for.

I was shocked this was not the VERY FIRST one suggested.

 

[Singularly Datarific]

Buy L4D2.
Open the console.
Type "thirdperson".
Viola! (an instrument)
Your gory first-person zombie game is now third-person!