An alien trader known to Neelix who offers to take a sentient weapon off Voyager's hands in the episode Warhead, and is destroyed when he tries to seize it.
Onquanii appears in the Voyager episode Warhead. After the crew beams aboard an intelligent device that turns out to be a weapon of mass destruction, Neelix gets in touch with Onquanii, a merchant he has dealt with, in the hope of trading for equipment the crew needs.
Onquanii soon works out what Voyager is carrying and offers to buy it, claiming he only wants to dispose of it safely. Janeway refuses to hand such a weapon to anyone.
The trader then attacks and tries to beam the warhead away. The weapon, which by then controls the Doctor's program, detects the attempt and triggers an overload in the transporter beam that destroys Onquanii's ship.