A spacefaring nomadic race of the Delta Quadrant whose society has been completely based upon the ritual hunt for a millennium, despite their advanced technological status. All other species are viewed as prey, not equals, but only challenging prey are prized and pursued.
Competition among males, hunting singly or in packs as "Alphas" and their subordinate "Betas," is for trophies or "relics" to display, including victims' skeletal remains, gutted organs and captured technology and artifacts.
An ancient galaxy-spanning sensor network taken over by the Hirogen, later disabled, was used by the U.S.S. Voyager to communicate briefly with the Alpha Quadrant and brought the groups into conflict.
In 2374, a visionary Alpha decided that the U.S.S. Voyager's holodecks would allow his people to continue the hunt tradition safely while regrouping to preserve their homeless, ever-dispersed culture. Despite his assassination, a younger successor agreed to follow through with the plan and use Kathryn Janeway's gift of a holo-program's optronic datacore. Unfortunately, the Hirogen misused that technology and programmed their prey to be overly cunning and adaptive — in order to make their hunts more "challenging" — and essentially gave those holograms self-awareness and a desire for liberation. Three years after receiving the holographic technology, disaster ensued at several Hirogen training facilities where the prey killed their hunters and escaped to free others of their kind and find a home to call their own.