Josh Brolin is Cable
Before we really knew anything about Deadpool 2, we knew that the time-traveling mutant Cable was going to be in it. In the post-credit scene in the first Deadpool, it was revealed that the sequel will finally be bringing the fan-favorite character to the big screen. The casting process was long and extensive, but Fox and the creative team ultimately decided to cast Josh Brolin as Cable, aka Nathan Summers. Even though Josh Brolin is already playing Thanos in Avengers: Infinity War, the Oscar-nominated actor managed to land the highly coveted role of Cable. He beat out other big names such as Michael Shannon and Brad Pitt, as well as Stranger Things star David Harbour, who was also in the mix. He may not have been everyone's first choice, but Josh Brolin is a damn fine actor and he is the man tasked with bringing Cable to life on the big screen for the first time in Deadpool 2.
Zazie Beetz is Domino.
While Fox decided to go with a huge name for the role of Cable, they went the opposite route for the role of Domino. Actress Zazie Beetz, who is best known for her role on FX's series Atlanta, landed the coveted role of Domino in Deadpool 2, beating out other big names such as Kerry Washington and Janelle Monae. If you aren't familiar with the character in the comics, Domino is an expert marksman and is very skilled in hand to hand combat, but her real power comes from her mutant power of being able to telekinetically manipulate probability. Zazie Beetz is going to be largely unknown to most of the audience who sees Deadpool 2, so we will pretty much get to see her as that character, since she is working from a bit of a blank slate, so to speak.
Jack Kesy is the main villain, is he Marvel's Black Tom?
20th Century Fox has tapped Jack Kesy (The Strain, Baywatch) to be the next major villain for Deadpool 2. It is not entirely clear which villain he will portray. But many sources are pointing to Deadpool villain Tom Cassidy, aka Black Tom. Black Tom is usually depicted as a villain up against the X-Men and archenemy of his cousin Banshee, but Black Tom has squared off against Deadpool numerous times as well. Black Tom is a mutant who first showed up in Marvel Comics X-Men #101 in 1976 and he can manipulate, bond with, and force energy through plants. He also uses a wooden object, often a walking stick that he can shoot blasts from. In addition, he is also a longtime partner with the impossibly strong villain Juggernaut. In the Deadpool comics, Black Tom was hired by Black Box, who can psychically retrieve, interpret, and store data from any form of electronic media, to hunt Deadpool. The idea of Kesy playing Black Tom is all currently speculation right now and he could very well be playing Black Box, since Deadline originally reported that their sources indicate that he will be playing a character named "Black Bob." There is no such character as "Black Bob," but you never know, maybe a new composite character will be announced, but that's doubtful.
Shioli Kutsuna is playing a mysterious new lead character.
After having recently starred alongside Josh Hartnett in the indie flick Oh Lucy!, Shioli Kutsuna is taking on a major role in Deadpool 2. But what that role is, is anyone's guess. There have been some rumblings that Deadpool 2 will introduce a brand new mutant never before seen in the comics. Is this that Mutant? Perhaps not, as the New Mutant in question is reportedly named Mike, with actors such as Killian Scott and Charley Palmer Rothwell trying out for the role. Though news of Kutsuna's casting came after this news broke. Perhaps this new mutant character has been gender-swapped. Shioli's hero or villain status hasn't been revealed yet. But before coming to the states, Kutsuna has been working in Japan as an actress for nearly a decade.