Toby Kebbell did not receive an Oscar nomination for portraying Koba in Dawn of the Planet of the Apes.
Toby Kebbell plays one of the apes, Koba, who still holds the scars given to him due to animal testing by humans. Just to recap on motion capture performances, actor's effort should not be waved away, but neither should the animators as there is some amplification involved. Well back to Kebbell's performance which technically fits right in with all of the Apes who are uniformly good in portraying the ape mannerisms of the characters, and they certainly do a great job of making the computer generated imagery feel more than just that anyways. They come across as characters, and not just merely special effects which is quite important. Kebbell has the meatiest ape role next to the Ape leader Caesar (Andy Serkis), as Koba, at first, acts a close confidant of Caesar's. This does not last long though once the human show up to utilize a dam in the Apes' territory in order to regain power. The idea of any sort of peace does not sit well with Koba who still holds a grudge against the humans.
Kebbell does well to bring a bit depth to Koba in the early moments where he voices his discontent with Caesar. It is a vicious anger to be sure that Kebbell expresses in Koba towards the humans, but he conveys how at least the seed was planted through the pain that came from his mistreatment. Kebbell actually has a bit of challenge presented to him in that Koba probably has the most actual spoken lines out of any of the apes. An ape speaking could come off quite silly but that's not the case with Kebbell's delivery. He gives the voice the needed animalistic intensity, while still having a clarity that feels right for Koba. Koba ends up being the antagonist of the film as Caesar attempts to make peace with the humans while Koba purposefully attempts to drum up conflict with the humans. The film though kinda drops any idea of Koba being a potentially sympathetic villain, and instead takes the approach of being basically a crazed mad ape who seems more interested in becoming the dictator of the apes than simply getting revenge against the humans.
Koba gets to run wild once the film's action begins. Koba has some rather memorable moments although a few of them do have much more to do with the film's direction, than really Kebbell's performance such as Koba's riding a horse through fire while firing a machine gun. Kebbell though does have one major moment for himself though when Koba steals a gun from two drunken idiot humans (who for some reasons were left in charge of the guns). Kebbell is rather entertaining in portraying the goofy antics Koba uses to disarm the men, both metaphorically and literally, making it appropriately disconcerting when he brings back to his deadly stare as he dispatches both of the men. That's a particularly effective scene and Koba makes for a menacing as well as enjoyable villain, due to just how insane Koba becomes. Kebbell's work certainly contributes to this greatly with his manner and particularly that voice of his. This is a good performance by Toby Kebbell, and I certainly have no complaints. I must admit I'm not nearly as passionate about this performance as many seem to be.