G.O.R.T.

Gort is an alien robot that appears in both versions of the science-fiction film The Day The Earth Stood Still. He is the protector of the visiting alien Klaatu.

In the original film Gort was responsible for a few deaths but was arguably more of a neutral character than an antagonist.

However in the remake Gort becomes a full-blown antagonist, being a far more substantial threat and has to be destroyed in order to save humanity.