Non human ... 
Source: http://www.ourcuriousworld.com/TypesofGhosts.htm
Next we come to one of the more controversial and, in some ways, more fantastic type of ghost- the Non human . This type not only is interactive and apparently intelligent, but, like the interactive personality, also frequently manifests emotions and sometimes seems to be on a mission. The only difference between it and the personality, however, is that this ghost is not of human origin.
If we work from the premise that the universe is a very large place likely home to countless races of intelligent, sentient beings-both physical and spiritual-it would be erroneous to presume that all ghosts are necessarily human1.
In fact, the ghosts of human beings (personalities) may make up only a tiny minority of all the spiritual beings in the universe, so another category is needed to differentiate this group from the purely human personalities.
Frequently referred to simply-and somewhat vaguely-as an 'entity', I prefer the term 'extra-celestial' for these varieties of intelligent energies that either once existed as physical creatures on another planet, or are creatures that have lived all their life in the spiritual realm as a being of pure spirit.
Unlimited by the restrictions of either human mortality or the vagaries of linear time and space, they are the free roaming and often ancient intellects which may well constitute the majority of all conscious and sentient non-corporeal life that make up the universe. They may even be inter-dimensional beings who exist on another plain of existence far outside of our venue or comprehension, and who occasionally choose to interact with us for some specific reason.
What those reasons might be are as varied as the stars in the sky, but probably have something to do with humanities' spiritual development (although, of course, this is purely speculative.)
Extra celestials are distinguished from personalities in the markedly different ways they interact with the living when compared to human based ghosts: whereas personalities tend to do and say very human things, extra celestials operate on a different level. They are frequently spiritual masters or teachers dispensing tremendous wisdom, or angelic beings willing and able to intervene in human affairs.
Additionally, extra celestials are extremely difficult to document, as they normally interact in more subtle and non-perceivable ways than do personalities. For instance, they rarely appear to the naked eye (though some mediums claim to be able to see them) preferring instead to work behind the scenes. They may also function essentially as guides for lost or confused personalities that are still caught in the earth plain, or as overseers of the spiritual realm sent basically to keep order. Further, just as there are malevolent humans to contend with, it is possible that there are malevolent extra celestials as well.
Could these entities serve as the foundation for many of the demon mythologies inherent in most religions?
1. Please refer Who or what was that in this web site.
Image source: http://listverse.com/miscellaneous/top-10-paranormal-abilities
Source: http://www.ourcuriousworld.com/TypesofGhosts.htm