The shared nature of the Marvel Cinematic Universe means that its movies are all mostly similar in tone, and despite the recent success of the R-rated Deadpool, according to Disney chairman Bob Iger, that's not likely to change any time soon.
"We don't have any plans to make R-rated Marvel movies,” Iger told shareholders on a call this week (via The Playlist).
Marvel Studios's movies may not venture into R-rated territory on its own, but both Netflix television series Daredevil and Jessica Jones carried the mature TV-MA, the television industry's most mature rating. According to the FCC, TV-MA denotes shows that are "specifically designed to be viewed by adults and therefore may be unsuitable for children under 17."
Additionally, several non-Marvel Studios movies featuring Marvel characters have carried that R-rating. In addition to Deadpool, the Blade film trilogy were rated R, as was the direct-to-video Man-Thing film. One R-rated film, Punisher: War Zone, was created under the Marvel Knights banner with Marvel Studios’ involvement, but was not connected to their other films, and predates Marvel being owned by Disney.