Because I don't know how many more of these I will be able to do for the time being, and because I want to show him since I got him and don't know how many other characters come before him, and also because I don't want this thread or my idea to die off,
Here is En Sabah Nur the Apocalypse:
(Or what I have thus far)
He is a very tall, muscular man (perhaps done with an actor and a green screen to make him look bigger than everyone, or perhaps he is just a big actor compared to everyone.)
He has a tattoo on his face (and I'd like to spread that tattoo to the rest of his body in some way.) He wears Egyptian clothing from the past, but I could see him updating his wardrobe too. Perhaps even dressing more like a king or something.
In that episode Mr. Sinister returns to his major threat status. He isn't the main bad guy though, his boss (who was always hinted at) finally shows up.
Apocalypse works mostly behind the scenes keeping himself mysterious. But then he becomes a major player.
He could have the same motivations as he has in the comics, but in the show you can see how he is greatly effected by his past. He is a man driven mad by past and his powers.
Again, if aliens don't exist in this TV Show then they wont be introduced here. So Apocalypse has nothing to do with aliens or an alien space ship that he turns into armor or anything like that. He is perhaps the FIRST mutant, his powers were to manipulate his own molecules.
His powers over time, especially during his hibernation he was able to grow, manipulate, and control, his powers more. But because his powers were so great to begin with he had to hibernate to stay alive. He is also a very powerful psychic, and whatever powers Xavier and Jean have. He can also manipulate the molecules of others, homosapien and homosuperior alike. He gave Essex his powers and the power to manipulate other's powers. He also manipulates the powers and emotions of other mutants to create his four other mutant to creat his Four Horsemen.
One of the problems I have with Apocalypse is that he is just too powerful and too inhuman. While that may work for the comics it wouldn't really work for the TV show. So to make him work, I think he would need to be more human. I also don't want to make him the final battle or so powerful that they have to stop him now or never and defeating him unites everyone. He may be a bigger threat than a lot of their enemies but he isn't the series finale. I would hope the show would continue after he is stopped. (It could even be presented like Lex Luther, he is not defeated just stopped for the time being or he stops himself.)