Many ghosts introduced in the first season appear to be the disembodied spirits of dead humans or other Earth creatures. Maddie once defined them as an "odd manifestation of ectoplasmic energy and post-human consciousness." This was supported by several ghosts' backstories, such as the Lunch Lady Ghost, Desiree, and Sidney Poindexter, which detail their lives as humans before becoming ghosts.
However, ghosts introduced in the second season onward became less human and more otherworldly in backstory and appearance. Creator Butch Hartman eventually stated that ghosts were in fact otherworldly monsters and creatures that came from the Ghost Zone, with no connection to human spirits.
Human Awareness of Ghosts
Throughout most of history, the majority of humans remained ignorant or in denial of the existence of ghosts, which notable exceptions including the Fenton Works, Vladco, and certain ghost hunters like Guys in White and The Groovy Gang and Scaredy Cat. People have a tendency to rationalize what they can and forget what they can't.
Amity Park was overrun with dozens of Walker's goons, causing as much chaos as they can. The Mayor proclaims Danny Phantom as Public Ghost Enemy Number One.
Eventually, Danny is taken by Walker/Mayor up to the entrance of City Hall, where "the Mayor" pretends to be hurt and dragged back into City Hall by Danny in front of two news crews, making sure Danny's prison is his own town.
The Casper High school board and the police department also appeared to be aware of the supernatural goings-on in Sunnydale, and often opened up ghosts attacks under order from the mayor, Ernesto Montez. The U.S. government was also aware of the existence of the supernatural to some extent, and even built special units specifically meant for hunting them.
In the early 21st century, the existence of ghosts became public knowledge, causing them to become a subject that capitalized on the fact that many humans experienced fear when seeing ghosts. Danny Phantom became the face of ghosts to the media, and began having her own bounty for a million dollars.
Ghosts did not require oxygen to survive, allowing them to survive in vacuum atmospheres and underwater. Vlad was unaffected by vacuum and Danny was even able to survive in the underwater of the home dimension of Earth.
However, ghosts did maintain some sort of breathing reflex, which allowed them to speak and gag reflex, which could affect them when choked such as Danny Phantom when Vlad Plasmius strangled himor when Danny was being attacked and strangled by a Vlad Plasmius. While they did not require air, they were shown to pant after losing energy. Ghosts were capable of speaking.
Ghosts' bodies typically take on an anthropomorphic figure. Ghosts typically have pale blue or green skin, and emit a distinct white aura around their bodies.
Some ghosts appear very similar to humans in appearance and behavior (Ember McLain, Youngblood, Walker). Some only vaguely resemble humans (Undergrowth, Vortex, Nocturn). Most are not humanoid at all, taking the form of shapeless blobs (Skulker, Bertrand), anthropomorphic animals (Wulf, the Vulture Ghosts), or monsters (the Ectopuses).
Ghosts' names have many different origins. Some ghosts retain their names from their previous life (Sidney Poindexter). Some have common human names or nicknames (Walker, Johnny, Kitty). Others choose their own names (Youngblood). Some are named after their powers or characteristics (Ember, Fright Knight, Undergrowth). Some ghosts' names are merely literal descriptions of what the ghosts are or do (Box Ghost, Lunch Lady Ghost).
Many ghosts have strong obsessions, which often lead them to their evil behaviors. For example, the Lunch Lady Ghost is excessively conservative about the cafeteria menu, Spectra is obsessed with her appearance, Walker is extremely strict with his rules, and Klemper has a compulsion to make friends. Ghosts' powers are usually related to these obsessions.
- Main article: Ghost Powers
All ghosts possess supernatural powers such as the ability to walk through walls, disappear, and fly. Ghost bodies are unaffected by gravity, so many ghosts have some degree of superhuman strength. Many ghosts possess other powers such as possession and ghost rays.
|“||On MY orders! Go to that world.||”|
–Ghost King, Reign Storm
Ghosts largely preferred working alone, though were sometimes found living in groups organized like packs or prides. These groups were commonly organized with the purpose of protection.
The leading ghost was known as the "Ghost King", usually the ruler of the group, the eldest one or the most powerful; in any event, the dominant ghost was the one capable of achieving the top position and enforce his authority through strength and violence.
The followers were commonly known as "Pariah's soldiers" or "minions" though sometimes they could also be referred as "skeletons". These were commonly the progeny of the master ghost, or ghosts that fell under the authority of the ghost king due to their own weakness or youth.
In some ghost bloodlines, there was a tradition of choosing new names for themselves. The Ghost King's bloodline was an example of this.
|“||The perfect combination of technology, past AND present!||”|
–Technus, Phantom Planet
When it came to modern technology, the majority of ghosts remained inept with most advances that humans possessed. Though some ghosts made use of human inventions such as newspapers, televisions and electricity; though made very little use of modern weaponry and were usually limited to basic hand-to-hand combat. Additionally, it was unusual for a ghost to use bladed tools for disembowelment as they already had teeth and claws powerful enough to do the job.
- "I am Box Lunch, daughter of the Box Ghost and the Lunch Lady!"
- ―Box Lunch[src]
Several breeds of ghosts are known to reproduce through normal pregnancy.
Ghostly children are the pure offspring of ghosts, presumably born through regular childbirth.
Several breeds of ghosts can increase their numbers by infecting beings of other species and transforming them into one of their own.
- Main article: Half-Ghost
A half-ghost is a human whose DNA is infused with ectoplasm. These humans possess many of the powers and abilities that ghosts do. Danny Phantom, the protagonist, is well known to be a half-ghost.