Deadpool is a box office smash by any standards, but the fact that it made more than $132.7 million in its opening weekend with an R-rating is particularly impressive. Inevitably, there is now much speculation about what other superhero properties will embrace the more restrictive rating, with both X-Force and Wolverine 3 potentially aiming for an R.

Producer Simon Kinberg, who oversees Fox's X-Men universe, spoke recently to Collider about whether more films in the franchise could aim for the higher rating. "I think there are some stories that could be R-rated," he said. "I don’t know what they are, I mean I think the mainline X-Men movies have their own tone, which is a more operatic tone. It's more dramatic, it is more PG-13 in a way. X-Force I could see being R-rated, and who knows?”

X-Force is a superhero team that was conceived by Deadpool's co-creator Rob Liefeld. They first appeared the 100th issue of Marvel's X-Men spinoff comic The New Mutants in 1991, and have gone on to include such heroes as Cyclops, Psylocke, Wolverine, Storm, and Colossus, as well as Deadpool.

Meanwhile, a catalogue that Fox made available at the recent New York Toy Fair revealed that the studio might also be intending for their third Wolverine movie to carry an R-rating. A photo published by Comicbook.com clearly displays an "anticipated rating."

Wolverine 3 is yet to start production, but last month star Hugh Jackman revealed that the film had a "full script." It is due for release in summer 2017.