1) Matt Damon
Fans got very excited back in July when Matt Damon revealed that he would only be interested in doing a superhero movie if his old pal Ben Affleck was directing. Naturally, when we found out Deathstroke will be the villain of the Batman solo movie, our first thought was that Affleck had taken Damon up on that offer.
After playing ace secret agent Jason Bourne for years, we know that Damon would be a natural as playing such a physical, formidable character as Slade Wilson. Deathstroke and Batman often have a very heated rivalry, and yet a lot of common ground too, so having two actors who know each other very well in those parts could make for an interesting dynamic.
It might sound like wishful thinking, but it should be remembered that the main villains in Batman movies tend to attract big names (Jack Nicholson, Liam Neeson, Tom Hardy, etc.). In that regard, Matt Damon would really be the perfect pick for Deathstroke.