Nice work. I think the first image could be improved if you cast a little shadow from the head onto the fist. Its seems a little flat as it is now because the overlapping is not effective on its own, maybe because the fist is hitting the face with the two outside knuckles which is unnatural and in reality would fuck up your hand. But it serves the illustration better drawn as it is, tone is the only thing I have an issue with.
Strange coincidence that every man whose skull has been opened had a brain.