The original X-Force was created by the half-cyborg mutant, known as Cable. Where the other X-teams believed in protecting humans from evil mutants, X-Force adopted a proactive attitude towards mutant terrorists. Cable's basic philosophy, which he related to his team, was "Get them before they get you".
The name was briefly used by a government organized media-driven team which later became X-Statix.
A new incarnation of X-Force was gathered his best trackers by Cyclops during the Messiah Complex, to hunt down Cable and the first mutant baby to be born after the Decimation. This team remains after this first mission, with the same philosophy as Cable's team but more lethal methods, led by Wolverine. Though Cyclops order it disbanded in the end of the Second Coming, X-Force continues to operate in secret, with both Archangel and Wolverine to lead it. This team ultimately disbanded.
In the aftermath of the Phoenix Coming, both Cable's team and Wolverine X-Forces reformed (Wolverine's being now run by Storm (who originally disapproved the concept during the Second Coming and its aftermaths) and Psylocke). In addition, a Multiversal team was also gathered by an alternate Charles Xavier to hunt down ten of his evil counterparts, but they quickly disbanded.
Eventually, Storm's and Cable's teams clashed, but later united in a single squad banding most of their members into a new strike team under Cable's lead.
After the creation of the new nation of Krakoa, a shadowy anti-mutant organization known as XENO launched a terrorist attack against it resulting in the deaths of Charles Xavier and several mutants. Thanks to “The Five”, Jean Grey and Cerebro, Xavier was brought back to life and decided that the only way to fight this shadowy organization was to respond in kind.
X-Forces have clashed on two occasions: When the original X-Force (led at this time by Domino) came to claim the name over the team who later became X-Statix, and when Cable's and Storm's fought over Hope Summers and a returned Bishop.