The answer to this question varies greatly based on the nature of each.
In the most commonly used Christian standards for demons, it is generally stated that one who is not devoted to the biblical god may be possessed by a demon. Demons also seem to be able to take control of animals (such as swine), and so provided a monster stands somewhere between humans and the rest of the animal kingdom, they may very well be a target.
This then brings into question the spirituality of a monster, namely: Do monsters have souls?
It seems to be that only humans are capable of salvation -- and the demon protection it is said to bring -- mainly because of their supposed souls. If a monster is soulless or otherwise incapable of carrying out the faith, it's pretty well done for in terms of possession.
Now, possession would seem to be a demon's greatest advantage, so if it is capable of using it, the fight is won and the monster is practically dead.
If it is out of the question, the next factor is the fighting prowess of each, whoever would win in a fight would be able to kill the other.
Generally though, I'd say a demon would be able to kill a monster.
Of course, if we go with any other mythology's definition of a demon, or a different type of monster, these results are all skewed.
It depends on the individual strengths and weaknesses of the monster and the demon. In some cases, a monster may possess abilities or powers that could allow it to defeat a demon, while in other situations, a demon's magical abilities or resilience may make it more powerful than a monster. Ultimately, the outcome would be determined by the specific characteristics of each creature involved.
depanding on lvl
in the deep wilderness against greater demon level 92
Humans can't kill a demon
Monster, it was a mythical "living" creature.
get a pair of dual fire blades go between the legs go to demon mode start slashin
The Ogopogo Monster, also known as the "lake demon" probably has the characteristics of eating people? He is a lake demon after all.
The only monster i know is the lesser demon and the greater demon. :P
魔鬼 móguǐ pronounce Maw gwey Demon , devil , monster
Look for a chest in the Demon Mines that have The Big Monster Food
erm your supposed to kill Elvarg which is lvl 80+, close to a lesser demon which is also about the same level In melzars maze you have to kill a lesser demon to open a door for a map piece.
You simply right-click them and select (Attack Dark Wizard Level-7) or (Attack Dark Wizard Level-21) Just like a normal monster. If you haven't gotten Silverlight yet do not attempt to kill the Demon.