All choices are purely fictional and my own. Actors chosen aren't currently in any of the cinematic universes to my knowledge, everyone is entitled to their own opinion. Enjoy.
X-Men
This is a casting of the first incarnation of the team, many more MCU phases for more Mutants to join.
Ralph Fiennes - Charles Xavier/Professor X.
Cillian Murphy - Scott Summer/Cyclops.
Joe Manganiello - James Howlett/Logan/Wolverine.
Jessica Chastain - Jean Grey/Marvel Girl/Phoenix.
Lupita Nyong'o - Orroro Monroe/Storm.
Ben Whishaw - Hank McCoy/Beast.
The Evil Brotherhood of Mutants
Daniel Day Lewis - Erik Lehnsherr/Magneto.
Karl Urban - Victor Creed/Sabretooth.
Charlize Therone - Raven Darkholme/Mystique.
Bonus
Aaron Taylor Johnson and Elizabeth Olsen - Pietro Maximoff/Quicksilver & Wanda Maximoff/The Scarlet Witch.
Now we know these two have already been cast in the MCU for Avengers: Age of Ultron. The two in question are being dubbed as "Miracles" in the MCU due to Fox having the rights to the X-Men.
If the rumors are true and Baron Von Strucker uses Loki's Mind Gem staff to create the "Miracles" then perhaps the story can be changed. Hyperthetically what if the mutant gene was always there hidden away but Von Strucker gave them the push they needed to gain there powers, also given that they're the son and daughter of Magneto in the comics if the X-Men were to be added to the MCU that would surely come up somewhere down the line.
Thanks for reading folks, let me know what you think of my fan-cast and theory in the comments below. Peace Out.
About The Author:
Hey guys, I am a comic book/movie enthusiast, who enjoys Fan-Casting, Any comic book inspired film and all things GEEK.