The Ghostmaster  (also known as the Ghostmaster General) is a powerful commander of many ghosts.
The Ghostmaster is considered to be very evil and powerful among all entities. He possesses an utter hatred of annoying mortals such as the Ghostbusters and Mimes, and is a being who commands both fear and respect from other spooks and spirits, unlike Samhain. After he realized how many ghosts the Ghostbusters had captured, Ghostmaster decided to deal with them once and for all. The Ghostmaster evidently didn't like to get his hands dirty and summoned three ghosts (Arborak, Ulyoth, and Nurgot) to capture the Ghostbusters and bring them to him alive. However, after the failure of his three ghostly bounty hunters, Ghostmaster vowed he'd defeat the Ghostbusters and melted their television set.
Some time later, he personally takes it upon himself to capture the Ghostbusters and take them to the Ghost World to be his personal servants.  Ghostmaster arrived with a squad of globes, similar to the one used by Nurgot. He tries to stop them by casting a force field around them. The field disables whatever technology comes within 40 feet of their presence.  Outside the New York City Public Library, he was defeated when the Ghostbusters learned that he was weakening and used an apparatus to remotely activate a trap hidden in a tree trunk more than 40 feet away.  When he was captured, it was Peter's turn to put the trap into the Containment Unit. When the power went out again, it was believed Peter Venkman neglected to put the Ghostmaster into the containment grid, until Winston Zeddemore reveals that he did put him in the grid. Peter forgot to pay the electric bill.
- Can summon entities
- Can open interdimensional portals
- Interdimensional Communication - Appeared in the Ghostbusters' television set
- Force Field Generation
- Can change his appearance to a more hideous form
- In the West End Role-Playing Game, there was also a character called the Ghostmaster, who was pretty much like the Dungeon Master from the popular role-playing game Dungeons and Dragons. 
- As a Class 11, he is on the rarest ghosts and considerably the strongest ghost by far. Which means that he is stronger than the Class 10 Toy Ghost or stronger than Gozer, Samhain, Mee-Krah, and Vigo combined. He is however, weaker than Cathulhu, who's power is described as being beyond the standard class system, as well as The Player, who is believed by many to be a Class 12, and Tenebraug, who is a Class 13.
- The Ghostmaster was created to be the show's main antagonist,  since the Ghostbusters have no recurring nemesis, which is atypical since most cartoons of its time would feature a main villain. But he was eventually written out of the series.
- He was one of the few ghosts to be slimed by Slimer.
- The Ghostmaster General is a reference to the Postmaster General, the executive officer that heads the United States Postal Service.
- Peter classified him as a Type A personality. 
- "Short Stuff"
- The Prosecutor ghost shows a picture of him to the Ghostbusters.
- "Revenge of the Ghostmaster"
- ↑ Ghostmaster's minions (2009). The Real Ghostbusters - "Short Stuff" (1988) (DVD ts. 03:05-03:07). Time Life Entertainment. Minions says: "Yes, O Great Ghostmaster."
- ↑ Ghostmaster (2009). The Real Ghostbusters - "Revenge of the Ghostmaster" (1989) (DVD ts. 05:35-05:42). Time Life Entertainment. Ghostmaster says: "I'm coming to get you and take you to the Ghost World where you will be my personal servants until you grow very, very old."
- ↑ Egon Spengler (2009). The Real Ghostbusters - "Revenge of the Ghostmaster" (1989) (DVD ts. 09:26-09:30). Time Life Entertainment. Egon says: "The Ghostmaster placed a force field around each of us that extends precisely 40 feet in all directions."
- ↑ Ghostmaster (2009). The Real Ghostbusters - "Revenge of the Ghostmaster" (1989) (DVD ts. 08:36-08:39). Time Life Entertainment. Ghostmaster says: "Even powerless, they are beginning to weaken my own powers."
- ↑ Ray Stantz (2009). The Real Ghostbusters - "Revenge of the Ghostmaster" (1989) (DVD ts. 09:38-09:41). Time Life Entertainment. Ray says: "According to "Who's Who in the Spirit World," the Ghostmaster rates as a Class 11."
- ↑ Peter Venkman (2009). The Real Ghostbusters - "Revenge of the Ghostmaster" (1989) (DVD ts. 05:50-05:51). Time Life Entertainment. Peter says: "Definitely a Type A personality."