Due to the enduring popularity of the X-Men brand, Marvel have created a number of spin off teams over the years, all featuring mutants who share Professor Xavier's vision of co-existence with humans in some form. Each have enjoyed varying degrees of success, but none have been more popular than X-Force, whose debut issue became the second highest selling American comic book of all time. Led by the mutant Cable, the original line up of X-Force were a more militant group than the X-Men, aggressively seeking out threats to mutants everywhere and occasionally resorting to lethal force when necessary. Despite initially enjoying enough popularity to rival Spider-Man and even the X-Men themselves, sales for X-Force eventually decreased, but in recent years, the team have been successfully revamped with a combination of original members and darker heroes from the core X-Men team, including Wolverine, Psylocke and Archangel. Rumors are currently flying around that an untitled project scheduled for release by Fox in 2018 could possibly be a X-Force movie and this would make perfect sense. A few key members of the team such as Sunspot and Warpath appeared in the future segments of X-Men: Days of Future Past and other characters that featured such as Blink and Bishop have ties with the team as well. If the rumors are true, then this was a smart way to begin establishing X-Force as a spin off team, gradually introducing audiences to new characters before they unite as a group. Furthermore, the villain of upcoming sequel X-Men: Apocalypse has intricate ties with Cable, the founder of X-Force, and it would be surprising if Fox didn't decide to use the character in some way. A X-Force movie is looking more and more likely by the day and if the anti-hero team Guardians of the Galaxy can hit it big, then there is certainly a huge possibility that a darker, more aggressive version of the X-Men brand can prove to be successful too.