Currently, the Marvel Cinematic Universe entry with the most speculation and rumors surrounding it is Deadpool 3. This namely involves which members of the X-Men will be present in the movie besides Hugh Jackman's returning Wolverine. The latest rumor relates to a somewhat overlooked villain that has frequently vexed the mutant team. Strangely enough, her presence in the film could also bring in a mutant who never got much shine in the Fox X-Men movies.
Source：https://www.cbr.com/deadpool-3-villain-kitty-pryde-role/
