Though Deadpool is currently filming in Vancouver, that doesn't mean they aren't continuing to add to the cast. Newcomer Brianna Hildebrand has joined the Marvel adventure as obscure mutant Negasonic Teenage Warhead. She joins a cast that already includes Ryan Reynolds in the title role, Morena Baccarin as his girlfriend Veronica, Gina Carano as Angel Dust and T.J. Miller as sidekick Weasel. Ed Skrein is the main villain, though his character identity has not been revealed. Tim Miller is directing.

Negasonic Teenage Warhead is a telepath with precognitive powers. She was created for the Marvel comics by Scottish comic book writer, playwright and occultist Grant Morrison, and quickly killed off. No further details about Brianna Hildebrand's character or role in the movie have been revealed at this time. She was first introduced in New X-Men vol. 1 #115, and was a student of Emma Frost. She was also a member of the Hellfire Club. And the character was, in fact, named after the Monster Magnet song 'Negasonic Teenage Warhead'. She will also be joined in Deadpool by X-Men Colossus, though he has yet to be cast.

It is not known how closely Brianna Hildebrand's Negasonic Teenage Warhead will resemble what was seen in the comic books. She was originally a pale-skinned mutant. Hildebrand will participate in physical and stunt training for her role, which suggests that she will be involved in some of the movie's bigger action set pieces. Brianna Hildebrand is known for her Annie Undocumented web series, which won best web series at the 2014 New York TV Festival. She is also a singer who independently produced her first album.

In Deadpool, Ryan Reynolds will play an assassin who is dying of cancer. He undergoes a procedure that leaves him twisted and scarred, but also imbued with superpowers. It is speculated that he will be exposed as part of a new Weapon X program that is being rebooted in this storyline following the events seen in X-Men: Days of Future Past.