Each entry on this page will have two rankings: fright factor and most common to encounter.  For the most part, these rankings will be inversely proportionate: the higher the fright ranking, the lower the common ranking and vice versa.

Apparition/Phantom

This is the general term for any type of spirit that is seen, heard, or witnessed in some way on this page.

Shadow Figures

Black flashes are spirits that often do not show themselves for a long time.  Usually you will see them only for a second as they cross your vision, or perhaps out of the corner of your eye.  Believed by many to be malicious spirits but many times they do not interact or harm the investigators in any way.  Most of the time the viewer will not fully believe he has seen the apparition as it is so quick.  The only potentially dangerous situation is that some places are rumored to have black shadows that will pass in front of a car.
FRIGHT FACTOR=2-6/10
COMMON FACTOR=4/10

Orbs

Orbs are the most basic form of "spiritual energy."  They appear in film as usually a white or blue circle or oval of light.  Recently, they have become a highly debated topic, whether they truly are an image if a spirit form or if they are just a reflection of dust or dirt in the air from the flash of the camera.  However this does not explain why orbs do not appear in all photos taken in the same area, or why they almost never appear in ordinary pictures taken.  Millions of people have taken pictures of things in the day and night for years and never have seen one, unless they are in a known or rumored haunted area.  Because of the difficulty in proving either side of this controversy, the question probably will not be solved in the near future.
FRIGHT FACTOR=2/10
COMMON FACTOR=9/10

Vortexes

Similar to orbs, they are believed to be a form of concentrated energy.  Vortexes come in many different shapes and sizes from wisps of light or foggy material to human like forms.  Again, these are highly debated whether they are legitimate signs of the paranormal, but are harder to throw out as fakes because of the intricate shapes and patterns in certain ones.
FRIGHT FACTOR=2/10
COMMON FACTOR=8/10

Ectoplasm

Ectoplasm looks like a thick fog, cloud, or a clear jelly like substance that appears in film.  Some have designs or faces in it and there are many different forms and colors that make up ectoplasm.  This topic is debated but not as highly as orbs and vortexes as it is not as common.  Believed by most to be signs of a paranormal presence.  Often appears on film when person/people feel the presence of something or that they are being watched.
FRIGHT FACTOR=3.5/10
COMMON FACTOR=7/10

Sensory Ghosts

These come in the forms of strong smells (roses are common), sounds such as footsteps or voices, cold spots, music, or paranoia (feeling of being watched).  They do not have enough energy to form an apparition or higher level of being.  Most of the time these are not frightening just eerie but sometimes they will come in the form of screaming which will be terrifying if you are not expecting it.  Many times, depending on the lay of the land, you may be hearing a noise reflection of something going on nearby so always check the area surrounding your location to make sure you were not hearing noises from a nearby party.
FRIGHT FACTOR=1-6/10
COMMON FACTOR=6/10

Ghostly Automobiles

May appear in areas where there has been fatal accidents and some are rumored to follow you until a certain point.  Depending on the situation these may be tame to absolutely terrifying, such as being followed by a large truck with no driver in the middle of nowhere. 
FRIGHT FACTOR=4-8/10
COMMON FACTOR=2/10

Angels

The counterparts of demons.  Because of the nature of most investigations, angels are almost never found during an investigation.  In fact, those who have come in contact or seen an angel do not report it as a haunting, but rather a miracle or religious experience.  The highest level of spirits, do not count on ever seeing one during an investigation. 
FRIGHT FACTOR=0/10
COMMON FACTOR=1/10

Demons

Avoid these at all costs.  Demons are very rare to just run into, most of the time they will come because of calling upon them.  However if you happen to be at a location and you feel intense hatred or evil for no reason followed with a rotten smell, this is one of the main signs of a demon.  When you hear of a spirit possessing a person or following them home this is most often the cause of a demon.  They are more powerful than the average spirit and have the power to manipulate things and people. If you may have a problem with one consult experts such as priests/rabbis/pastors.
FRIGHT FACTOR=10/10
COMMON FACTOR=1-2/10

Poltergeists

Most often, these haunt a house or other type of building, not a land area.  Poltergeists may be as mellow as discreetly moving objects or throwing objects noisily around the room.  Sometimes they will even physically abuse the person that is being tormented.  Often they feed on the fear of whoever is living in the house/building, allowing them to gain more strength.  Most of the time though, these will take the form of mischief rather than having the desire to frighten.  There are many famous poltergeist accounts throughout history.  Poltergeists will often start off small and only cause questioning in the mind, but will grow worse and more frightening as time passes.
FRIGHT FACTOR=8/10
COMMON FACTOR=2/10

Revenge/Caretaker

A broad term that refers to a human spirit that intends to either frighten, hurt, or take care of a certain location.  Some old cemeteries are rumored to have cranky old guardian spirits that do not want people there and chase investigators out.  Revenge spirits have been murdered or wrongfully killed when they were human, such as women wrongfully burned for possibly being a witch during the Salem Witch Trials.  These spirits will definitely interact with the viewer and attempt to frighten them off the property, some may replay their death, and others may perform frightening acts or change their shape in order to alarm the viewers.
FRIGHT FACTOR=5-9/10
COMMON FACTOR=5/10

Replay/Residual

These types of spirits are ones that will go about normal activities, perhaps unaware that they are no longer alive.  Also, they may replay the last moments before their death.  This is one of the most common ghost types investigators will experience as old mental asylums or hospitals, old battlefields, or colleges/schools are all common spots of replay ghosts.  These may be very frightening or not at all, depending on the location and the circumstance.  Most often, there will be no interaction between you and the spirits and they will go about their way without acknowledging your presence.
FRIGHT FACTOR=2-8/10
COMMON FACTOR=6/10

Crisis Apparition

Another highly debated topic in the paranormal world.  Who hasn't heard an urban legend somewhere along the line of someone is deathly ill and a ghost of themselves appears to a family member who lives far away calling for help?  This is a crisis apparition, one that appears when the person is under extreme duress.  Most people who have had contact with these spirits do not even realize that it is not in fact the actual person, so generally these are rare and not frightening.
FRIGHT FACTOR=0-1/10
COMMON FACTOR=1/10

Animals

The most common form of spirit animals are dogs, also known as hell hounds.  Often these spirits are very frightening as they appear larger than normal size, have glowing red or yellow eyes, and have unusual speed and quickness.  Often these hell hounds are accompanied by demon existence nearby.  There have been reports of people being severely injured by these malicious spirits but are largely unconfirmed.  Other types of animals are not nearly as frightening as most do what they normally did when they were alive.
FRIGHT FACTOR=1-10/10
COMMON FACTOR=3/10

Unhuman Spirits

Not to be confused with animal ghosts, these spirits are usually hybrids of animals and like nothing that has ever been seen before.  They are not or not have ever been human. Witnesses are often unable to describe them completely.  The vast majority of these spirits are powerful and are looking for ways to frighten or hurt viewers.  Avoid locations that are rumored to have these types of spirits as they are almost always bad news.
FRIGHT FACTOR=8/10
COMMON FACTOR=3/10