Nigh-unstoppable, Jedi-killing warmachine of a cyborg that had his flawless kill-streak interrupted only when Windu suprise partially force-crushed his chest. Before that he did some really ridiculous, badass shit and being a very big danger. Especially if you were a Jedi. Uses four arms only when he's in a real pickle. >Clone Wars Grievous
Much less of a threat than the Tartakovsky one. Constantly uses four arms and still doesn't get the needed results. >Revenge of The Sith Grievous
NO. BLOODY. COMMENT
My headcanon is that the two latter Grievouses are actually degrading clones while the original one got frozen in carbonite because he accidentally stumbled upon info that the Banking Clans were behind the explosion of his ship and that his mind was altered by the Separatists. They managed to catch him and freeze him (because killing him off would've been a horrible waste), then used his genetic materials (and some stolen Caminoan tech Sidious got his hands on) to create clones that were implanted his altered memories. This however caused the clone Grievouses to have erratic minds and degrading combat capabilities. Thus the original Grievous is still stuck somewhere in carbonite because everyone forgot about him.