Copycat, whose real name is Vanessa Carlysle, has shapeshifting and power mimicry abilities, hence her rather on-the-nose moniker. She first appeared in "New Mutants" #98 disguised as Domino, later revealing herself to be Copycat in "X-Force" #19. Like Deadpool, she was also part of the Weapon X program at one point in her life.
Baccarin was cast in "Deadpool" last month, though her role was previously unannounced.
Let's do this. pic.twitter.com/pNqcCGReSz— Morena Baccarin (@missmorenab) March 19, 2015
"Deadpool" co-creator Rob Liefeld, who likewise co-created Copycat, further confirmed by reposting the image to his Instagram account with the caption "1st appearance Vanessa is New Mutants #98."
"Deadpool" is scheduled to premiere on February 12, 2016.