Deadpool's Negasonic Teenage Warhead appeared onscreen in a vastly different form than she originally took in comic book, with an altered powerset and a new look. The film's concept artist Joshua James Shaw has shared the character's visual evolution, which originally took a much more "goth" direction.
“This is where the first set of Negasonic Teenage Warhead sketches came out of,” Shaw said on his personal website. “It turns out I was going overboard with the goth look for NTW and Tim wanted us to do a pass of her in a suit close to what Josh Middleton designed for his New Mutants covers. Then the costume department would put together something over the suit to give her the goth look.”
Shaw also helped design the Deadpool suit seen in the leaked test footage, which was also used for the final film.