The Legion of Frontiersmen is a civilian nationalist paramilitary organisation formed in Britain in 1905 by Roger Pocock, a former North-West Mounted Police constable and Boer War veteran.

Headquartered in London, the Legion of Frontiersmen formed branches throughout the Empire to prepare enlistees for war and foster vigilance in peacetime.

Despite their efforts, the Legion never achieved significant official recognition, in part because many Commonwealth nations' laws prohibit militia groups.

Casualties in the First World War devastated the Legion of Frontiersmen, and except for a brief resurgence in the interwar period, a series of schisms and sectarianism prevented attempts to reinvigorate the movement.

[1] Various Legion of Frontiersmen groups still exist throughout the Commonwealth, but as a whole, it has been unable to define its niche post World War II; especially because the organisation generally refuses to provide information about its activities to prospective applicants.