I've been wondering about this for a while now. When I was toying around with ideas for a new race, one of my ideas was to make them as deadly in close combat as the Tau are at Shooting, but it occurred to me that such an army may already exist.
There are a lot of potential candidates in the WH40K range, so what army do you think is the most destructive, fiercest, and best at ripping their foes apart in bloody melee?