Deadpool so far has been very firm in its character lineup. By that I mean characters known to associate with Deadpool. Like Weasel, and Copycat. Now though, a very obscure member of the Marvel Universe is set to join the film.
Negasonic Teenage Warhead, I kid you not that’s her name, has been revealed as being a part of the movie. She’ll be played by Brianna Hildebrand, who is apparently going through physical and stunt training to prepare for the role.
In the comics, NTW was a member of the X-Men, more specifically a member of Emma Frost’s psychic students who were on Genosha. She subsequently died in two different arcs (comics everybody).
Though psychic in nature, it appears that NTW may be joining the ranks of the Morlocks, who have been noted to be in the film. Time will tell I guess.