That’s Wrecking Ball, the newest playable character coming to Overwatch. The design inspiration is clear. He’s your childhood pet hamster in the plastic exercise ball you rolled around on the floor. In Blizzard’s game the hamster is super-intelligent and bloodthirsty, and his plastic ball is now a combat mech. It makes sense.
The hamster’s name is Hammond and according to the lore he escaped from the same Secret of NIMH type laboratory as Winston before becoming an Overwatch hero. You know what that means! Erotic gorilla-on-hamster fan art coming soon!