Killerwatt is a character in the episode Killerwatt in the television series The Real Ghostbusters.
Killerwatt is a powerful entity who feeds on electricity. It sends its ghost minion out to attack power lines, eventually resulting in a blackout. The Ghostbusters have to rig up a stationary bike to generate enough electricity to properly power the containment unit so that it doesn't suffer catastrophic failure.
The Ghostbusters managed to track down Killerwatt at the power plant. Winston Zeddemore deduced the ghost was drawing its power from the electricity. When the Ghostbusters failed to turn off the power, Slimer saved the day and pulled the plug himself. The host body of Killerwatt crumbled away and the Ghostbusters were able to capture it.