The region of the Delta Quadrant inhabited by the Malon, an industrial people whose freighters carry lethal antimatter waste out to dump it in other parts of space, encountered by Voyager during its fifth season.
Malon space is the home region of the Malon, whose civilisation runs on a form of antimatter power that leaves behind huge quantities of theta radiation. Their homeworld, Malon Prime, is said to be a beautiful place, and it is kept that way by exporting the waste.
Voyager first meets the Malon in Night, set in 2375, when the controller Emck is found emptying his freighter through a vortex into the starless Void and poisoning the beings who live there. He turns down Janeway's offer of cleaner technology because it would put him out of business.
The Malon return in Extreme Risk, racing the crew for a lost probe, and in Juggernaut, in which Voyager must stop a crippled freighter from exploding and contaminating a whole sector.