doomsday machine

"They say there's no devil, Jim, but there is....
RIGHT OUT OF HELL!!!!
I SAW IT....!!!!!" - Starfleet Commodore Matt Decker of the USS Constellation NCC-1017, describing the Doomsday Machine.

A very destructive and dangerous gigantic mecha from the Star Trek franchise. It appears in Star Trek: The Original Series.

The Doomsday Machine is a very powerful and virtually unstoppable automated massive alien robot machine capable of destroying entire planets using powerful pure anti-proton beams. The machine then uses the planetary debris and other remains as its main source of fuel, making it a self-sustaining robot weapon.

It resembles a giant mechanical worm floating in space. Its main superstructure is made of pure neutronium, making it resilient to most forms of energy weaponry.