Whether you prefer "Warmech" or "Death Machine," just don't call it the wrong thing, or it might show up at the worst possible time.
You only have a 3-in-64 chance to encounter Warmech, and it only appears when you get into a random battle in the Flying Fortress, but I love everything about it: the weird choice of salmon pink for the color scheme, its one big eye just right in the center, always looking slightly up and to the corner. It reminds me of a bad early-gen Pokemon, but it certainly doesn't fight like one. Warmech is a beast, and it's called the first "superboss" in Final Fantasy, referring to optional fights against massively difficult monster. It boasts the same HP as the end boss, not to mention the ability to regenerate 5% of its massive health pool every round. Not only that, but it also has access to Atomize, an incredibly strong non-elemental spell that hits the entire party.
The fantastic thing about Warmech is that it's this odd robot monster that launches nukes, and Final Fantasy 1 takes place in a medieval fantasy world. This would be like if in the original Dungeons & Dragons, there was a secret entry in the Monster Manual for Tinker the Robot.