Killerwatt  is the "grand ghoul," "the ethereal master of many," and commands an army that feeds on electricity. He was behind the blackouts as he had other ghosts attacking the power lines. The Ghostbusters traced a P.K.E. surge to a power plant in Brooklyn.
Killerwatt and his army of ghosts began to feed off electricity from a power plant in Brooklyn. As a result, New York City suffered a rash of power failures. When Killerwatt's army began to travel through power lines and haunt Stacy's Department Store, Mayor Lenny hired the Ghostbusters to capture them. While disposing of the captured ghosts in the Containment Unit, Killerwatt's army struck again and forced the team to rig up a peddling apparatus to keep the Unit from suffering another catastrophic failure. Egon then traced the P.K.E. surges to the Brooklyn power plant.
After stumbling into the power plant, Killerwatt appeared to the Ghostbusters and attacked. The Ghostbusters mistakingly tried to charge Ecto-1 with its electricity blasts and caused the car to become possessed. After following Killerwatt into the plant, the Ghostbusters were separated and brought before him in the control room. He then possessed equipment in the room and transmogrified it into a giant monstrosity. Shielded by the plant's power, Killerwatt was immune to the Ghostbusters' assault.  Winston deduced he was drawing power from the plant's generators and they had to shut them down. Killerwatt countered and created a wide chasm between the Ghostbusters and the main switch. Luckily, Slimer found the main plug and yanked it from the outlet. Killerwatt's host body lost power and fell to the ground. Killerwatt vacated the body and was trapped by the Ghostbusters. With power restored to the city, Mayor Lenny quickly organized a victory parade for the Ghostbusters.
Killerwatt is a very powerful ghost. Some of his powers include:
Electric Bolts: He can shoot bolts of electricity from his eyes.
Possession: Just like the his minions, he can possess anything electrical.
Flight: Standard ghost power.
While in his giant machine form:
Superhuman Strength: While possessing the giant machine, he is shown to easily destroy a platform.
Electric Absorption: He is shown to absorb electricity from the generators.
Proton Absorption: He is one of the few ghosts who can absorb the proton blasts. 
Animation: He is shown to animate the power plant into a giant monster.
Electric Bolts:: He can shoot electric bolts, in this form the bolts were more powerful.
He is a leader of ghosts and as such is a major ego, and laughs a lot while causing trouble for the Ghostbusters. Also, when the Ghostbusters said he'd win over their dead bodies, he responds with "Dead bodies are my specialties", indicating that he enjoys killing mortals if he must.
- When Killerwatt absorbs Peter's Proton Stream, Peter says,"Mikey likes it," in reference to the fictional character Little Mikey from the famous 1972 Life cereal commercial.
- On page four of Ghostbusters Issue #4, Killerwatt makes a non-canon cameo as a magnet holding up a newspaper clipping. The magnet is based on his host body.
- On page 12 of Ghostbusters Issue #8, Killerwatt makes a non-canon cameo on one of the cans in the garage bay.
- On page 10 of Ghostbusters Issue #14, Killerwatt makes a non-canon cameo on Egon's batteries.
- On page 20 of Ghostbusters Volume 2 Issue #2, Killerwatt is referenced in the lower right corner of the pack.
- On page two of Ghostbusters Volume 2 Issue #12, Killerwatt makes a non-canon cameo on an image of the electrical panel Egon is near.
- On page 15 of Ghostbusters Volume 2 Issue #18, the Killerwatt makes a non-canon cameo as the magnet on the He-Man party flier.
- On the Convention Cover of Ghostbusters: Get Real Issue #1, Killerwatt makes a non-canon cameo right of Winston Zeddemore.
- As primary antagonist of the episode
- "Xmas Marks the Spot"
- A cameo inside the Containment Unit.
- ↑ Killerwatt (2009). The Real Ghostbusters- Killerwatt (1986) (DVD ts. 18:52-18:53). Time Life Entertainment. Killerwatt says: "I am Killerwatt."
- ↑ Winston Zeddemore (2009). The Real Ghostbusters - "Killerwatt" (1986) (DVD ts. 19:13-19:15). Time Life Entertainment. Winston says: "The power plant's electricity's shielding him!"
- ↑ Ray Stantz (2009). The Real Ghostbusters - "Killerwatt" (1986) (DVD ts. 19:10-19:12). Time Life Entertainment. Ray says: "Incredible! It's absorbing full force proton streams!"