What is it?

From a distance it appears as a huge puppet. It lurches and staggers, swinging its swollen limbs, flinching at invisible beatings, knees jerking, driven by forces blind to the damage of its own body parts. On closer inspection the stench of decay becomes apparent. It is animated but terminal, a careless leper. Parasites find comfortable homes deep beneath its skin. They thrive and multiply without ever needing to give anything to their unwitting host.

This grotesque being used to know people. It understood loyalty, humour, and personality. Now it craves human brains for no other reason than to fuel its own metabolism. Its ability to digest them has degraded. It needs more and more of them, but the larger ones are becoming harder to swallow.

You can't speak to it or reason with it. You can't stop it without extreme violence. Just wait for it to fall apart by itself. Then it will be consumed by others of its ilk, desperately trying to extend their corporeal existences.