Butch Hartman: Ghosts are actually creatures from another dimension and are not actually the spirts of dead people.
Ember McLain: Has a whole song implied to be about her death and/or the circumstances that led to it.
Sidney Poindexter: Is explicitly mentioned to be a former human student of Casper High prior to him dying.
Desiree: Is shown as a human in the distant past prior to becoming a ghost and is explicitly mentioned to have died in the past.
Cujo: Has an entire episode where a bunch of Axion Labs employees basically just say “Boy it sure is a good thing we put down all those guard dogs” before a ghost dog with a collar explicitly stated to belong to Axion Labs breaks into the building and won’t calm down until it enters a room that belonged to the Axion Guard Dogs and finds a dog toy heavily implied to have belonged to them in life.





