Bureaucratic Delta Quadrant people with strict rules on passage through their space, into which Seven of Nine fled while following a Borg signal.
The B'omar control a region of the Delta Quadrant and are wary of outsiders, insisting on careful negotiation and fixed routes before any ship may cross their territory.
In The Raven, Janeway was negotiating passage when Seven of Nine stole a shuttle and entered B'omar space, drawn by a Borg homing signal to a nearby moon. Tuvok followed and Paris took a second shuttle across B'omar lines. On the moon, Seven found the wreck of the Raven, the ship she had lived on with her parents before the Borg took them, as the B'omar opened fire on the intruders.