The Sentry Golem

This would be a Utility Mob. I imagine it as rather drone/wasp like, and being built with a single gold block, and a pumpkin(naturally).

It would fly around at 6 block above the ground. This is so it won't get too confused when leads are attached to it, and it would fly over short walls and pits, but not ravines and towers.

I don't want it to be ranged; I imagine it swooping down like a phantom onto hostile mobs, hurting them, and then flying back up quickly to strike again.

Overall, I think adding not only a new utility mob, but a ranged player-loyal mob would improve defenses and combat.