You may have thought the art of Brute Force was of a giant expressing his rage, spiked-club style, on the towers of a castle. He is a giant-sized brute, but that's actually just the effect of the spell.
Brute Force art by Wayne Reynolds
The figure in Wayne Reynolds's art is actually a Keldon, a member of a grey-skinned race of savage Dominarian warriors. Keldons are technically human; this guy was originally closer to the size of the unfortunates he's knocking clean out of their protective tower. But their rage... well, let's just say the warrior in the picture didn't need his temper to get +3/+3.
You can see other Keldons depicted in the Time Spiral Block on cards like Keldon Halberdier, Keldon Marauders, Radha, Heir to Keld (she's half-Keldon), and on a Future Sight card.