The villains in the X-Men movie franchise have been something of a mixed bag in terms of their quality. The likes of Deadpool in X-Men Origins: Wolverine and Juggernaut in X-Men: The Last Stand were absolutely terrible, while the likes of Sebastian Shaw in X-Men: First Class and the Sentinels in X-Men: Days of Future Past were pretty good.
Mostly, however, the franchise has relied on the ongoing presence of Magneto to provide the threat – and he has been portrayed brilliantly by both Michael Fassbender and Ian McKellen.
Omega Red

Omega Red is by no means as powerful as the likes of Apocalypse, but if Fox want to give an individual X-Men member another movie in the future, he would certainly be an awesome foe for that character.
There are plenty of other individuals for whom Omega Red could provide opposition, however, such as Colossus or Kestrel, so if any of those guys (or various X-Men spin-off teams) were to get movies of their own, he could appear.
Read More: Omega Red in Deadpool 2?
His origins would need to be changed – he was part of an attempt to recreate Captain America’s super soldier serum and Cap isn’t part of Fox’s franchise – but his Carbonadium tentacles would look awesome in live action and his abilities to secrete a sickness-inducing pheromone and absorb opponent’s life-forces would be awesome to see on screen.

