He is portrayed by actor Michael Ironside.
Overdog McNabb is a cyborg ruler of the planet Terra XI, which was a failed colony that fell victim to a deadly plague and civil warfare a couple of years ago during the stalemate. In the year 2013, the planet was explored later on colonized. In the year 2021, the planet had an outbreak of the P.S.I. Plague, a year later Overdog was a former doctor who was sent to Terra XI with some other doctors including Patterson assigned to the interplanetary medical expedition to fight the P.S.I. Plague outbreak. Overdog and Patterson ended up quarreling and became enemies. Overdog betrayed Patterson and assumed dictatorship over the planet and ruled from the Forbidden Zone in a fortress known as the Graveyard". In the year 2031, the medical team vanished and Terra XI became quarantine restricted.
In the year 2036, Overdog rules Terra XI, along with his main henchman, Chemist, who is responsible for some genetic mutations of others, including children. Overdog entertains himself and his men sometimes with some prisoners he sends through the "Death Maze" with lethal obstacles, hazards and traps. He sends one prisoner in the slave pens at a time to see if they can make it through the maze.Overdog sends some Trikers out and the Trikers ambush the train Patterson, Duster, Jarrett, and the three women are on. Overdog sent out his Trikers flying in machines called "vultures" cause of their appearance of vultures to scout out looking for women to have peasures with and drain their energy which Overdog needs to sustain himself since he is getting old. Overdog uses a maching called the "Fusion Tube" to drain energy from living people to sustain himself.
Overdog's vultures capture three Earth women named Nova, Meagan, and Reena, who are stranded on Terra XI after their escape pod from an ion storm damaged the tour ship. The escape pod landed them there and were rescued by Patterson, Duster, and Jarrett.
Overdog's vultures captures the tree women and bring them to the Zone. Chemist takes them to see Overdog and Overdog has a moment with one of them. Overdog holds the women captive, not knowing the women are going to be rescued by Wolff, a fomer soldier, now bounty hunter along with Niki, Washington, and Duster and Jarrett. When they arrive at the Graveyard, things get rough for Overdog, but Niki is captured and taken to Chemist, who brings her to Overdog and has her put into the death maze. Wolff rescues the women, but goes back to help Niki. Niki makes it through the maze, but Overdog lies to her about setting her free isf she makes it through and has Chemist prepare the fusion tube.Overdog tells Niki that he needs her energy to live longer, as she is weakened by the fusion tube, explosions happen and Wolff breaks in the area. Chemist is killed by Wolff and he and Overdog face off. Wolff shoots at Overdog with his gun he put missles on and does end up shooting at some cables near Overdog and then shoots at Overdog. Thinking that Overdog is dead, Wolff goes to free Niki and Overdog catches Wolff with his metal claw, hurting him. Overdog tells Wolff about how he is full of energy. Wollf tells Overdog to let Niki go and he will take her place and Overdog says "How do you know I will not doublecross you and take you both." When Wolff sees one of the damaged cables moving on the floor, he then grabs the cable and then jabs the sparking power cable into one of Overdog's claws. The power feedback fries Overdog and thus causes cascading blowouts throughout the entire fortress, killing Overdog while Wolff, Niki, Washington, Duster, and Jarrett escape while the Graveyard explodes and falls apart.