I would like to propose the following contest for the best cinematic villain in the scifi/fantasy genre: DARTH VADER vs. LOKI.
They’re both from space, and they both have mad combat skills. From there, however, they diverge, sort of.
Their weapons are impressive but different. Darth Vader has that classic light saber while Loki has (well, temporarily) a wicked-looking sceptre fitted with the Mind Stone in disguise.
Darth Vader has that telekinetic thing going with The Force, but Loki can use illusion of mythical dimensions. This more or less leaves us with something on the order of an unstoppable force aimed at an untouchable target.
Both characters have appealing nuance, a mixture of the honorable and the deplorable. In terms of origins, Loki, with his ambitions and father issues, has the better-written back story. His is also a more complete character study, but Darth Vader has the more iconic image (not to mention his voice and the sound of his breathing). His story arc is also complete while Loki’s is still unfolding.
And the winner is…
The Walt Disney Company, which now owns the rights to both the Star Wars and the Marvel franchises. A number of military, political, and socio-economic implications can be drawn from this and applied to real life, but I will leave that to the imagination of my readers.