I've been planning on responding to this topic for a long while now, but (I'm mentioning this in all the threads I needed to catch up with in my backlog, with this one being the last on my list unless I find more when I go through my tabs) I haven't had the time due to a lot of problems coming up on my end and these problems haven't really gone away. I'm going to get this out of the way now, and my response is actually in two parts to an extent. I won't be going into the full detail I could by any stretch of the imagination.

In response to the discussion topic presented by [@Halvtand] at the beginning of this thread, I think bad writing can constitute to the inability to establish the difference between the two - as was suggested to an extent earlier - but this can often be as much a problem of defining what makes a 'monster' and what doesn't. What I mean by this is that it's difficult to establish the difference between an animal and a monster if you don't actually have an established [i]definition[/i] for 'monster' in the first place, and how much - if any - difference there is between animal and monster can often be very reliant on this information. Failing to miss details like this is part of what makes writing bad in my eyes. People have suggested numerous concepts for what defines a monster, but none of them will apply universally to every single setting.

The literal definitions of 'monster' also need to be taken into account.

[quote=Monster]1.
A large, ugly, and frightening imaginary creature.

2.
A thing of extraordinary or daunting size.

3.
A congenitally malformed or mutant animal or plant.[/quote]
1. I consider this definition the most complicated, as it's largely subjective to the universe. Any creature which meets the requirements of being a 'monster' in this setting is determined by their fictitious nature, which means that animals wouldn't be viewed as 'monsters' in this definition, nor would something considered a 'monster' in reality be considered one in this setting if they're natural to the world of that setting. With this definition, a character wouldn't call a dragon a 'monster' if dragons are commonplace in the setting, whereas an elf [i]would[/i] be considered a 'monster' if their existence in that setting isn't widely accepted among the population. I'm aware that elves don't meet the requirement of being large or ugly, but not all things classified in fantasy settings as 'monsters' are those things. A lot of writers will also make 'monsters' some sort of creature that comes from another dimension - such as from Hell or an eldritch universe - and this usually creates a much better separation between animal and monster.

2. This definition is mostly irrelevant, because it means that any particularly large animal is a 'monster'. A whale, by its very nature, would be considered a 'monster' in this context due to its size being overwhelming in comparison to a human -- assuming that the perception of humans is the focus point of the narrative (which it usually is). In a story where ants are the main characters, a human [i]is[/i] a 'monster' by this definition, and certain children's films have played with this idea.

3. Using this definition, a 'monster' is a creature which has been mutated through a disease or birth defect. With this in mind, in the context of the setting it's largely a matter of whether or not this creature is naturally the way it is or if its qualities are a result of some sort of birth defect or corruption. In fiction, I would imagine being malformed or mutated through supernatural or paranormal means would also make something a 'monster' in this regard. A standard dog wouldn't be considered a 'monster', but one that's been mutated into a Hellhound by demonic forces would be, though this also makes it cross into the first definition I listed.

As for the discussion about whether or not humans (or animals for the matter) can be viewed as 'monsters' in the real world - a discussion which is clearly off the main topic - I'm going to give some of my thoughts in a hider below this. Keep in mind that this discussion is actually a large part of my philosophy, and not something I'm merely expressing a random opinion about. My views are fairly controversial and I don't expect everyone to agree with me, but if anyone decides to get into an argument with me over their own insecurities I will [i]not[/i] be humouring them. As a human, I have the power to overcome my base instincts, and that includes not feeding into flame wars or associating with people who're unable to debate like an adult. These comments aren't directed at any person in particular -- they merely present a warning to those looking for an argument. Also, since this is off topic to an extent (not that it's stopped other people, and I will indeed return full circle to the original question present by the opening post), you don't need to read it if you don't want to (not that people read my whole posts a lot of the time anyway). I simply feel the need to say it due to other people going off the topic and touching on a few nerves with me.

[hider=What I consider a 'monster']
[i]"He who fights monsters should see to it that he himself does not become a monster. And if you gaze for long into an abyss, the abyss gazes also into you."[/i] 
[b][i][s]   [/s] Friedrich Nietzsche (Beyond Good and Evil)[/i][/b]

Not that I'm a follower of - or even in agreement with - the philosophy of Nietzsche, because I'm honestly not and my philosophy is entirely my own for the most part (any similarities to the works of any other thinkers are mostly coincidental), but this quote nevertheless has a ring of truth. Within this definition of 'monster' - the one which I hold closest as reality - is the implications of corruption, malevolence, or 'evil'. By this definition, human beings are almost certainly capable of becoming 'monsters', but I don't believe this is a trait that goes outside of our animal instincts -- I believe it to be [i]part[/i] of our animal instincts, and I consider claims otherwise to be ignorant and juvenile. I don't view humanity as an entity that embodies all of the sins of this world, but as an entity with the power to [i]overcome[/i] the sins of this world. This has put me at odds with many people - both religious and non-religious - throughout my life, but I won't be getting into a religious debate here -- anyone who fishes for one will be ignored.

You can think of humanity as a corruption in this world because it has polluted the planet, but humanity has only done so in the pursuit of means to further its own survival (this includes war, which at its root is caused by survival of the fittest between groups of people, regardless of how many people want to blame other reasons), making their actions a direct part of their animal nature. If anyone is to blame for that, it's the world for creating us so incompatible with the system in the first place -- our flaws are in our programming, per se. It's also part of animal nature to form civilizations and societies, though since humans have higher reasoning and diplomatic facilities the potential of these societies is greater. Herd conformity is animal nature, not merely human nature. The problems which come as a result of technology and science aren't inherently flaws in humanity either, but flaws in misusing the tools we have (or, in some cases, creating tools that should never have existed). Do you honestly think an animal would hesitate to use a gun to ensure its survival if it had the means to? I think not. Animals don't hesitate in - nor feel regret for - killing others in order to survive, or in some cases as part of their reproductive cycle or method of weeding out the 'weak', so why should humans be demonized as worse simply for doing the same? I'm not saying these actions are acceptable and should not be viewed as abhorrent -- simply that only choosing to make a point of them when they're at the hands of humans is bias of the worst calibre.

So, in my eyes, what constitutes to being a 'monster'? It's actually simple. I believe those who don't overcome their base instincts are 'monsters'. Humans - as a whole species - have the power to overcome their base instincts through their will and wisdom, and failure to do so is the result of virtually all atrocities that are committed by humans (the things which would make them be viewed as 'monsters'). Humanity isn't evil in my eyes. Nature itself has a predisposition towards what I consider 'evil', and it's something we should overcome. What I consider to be 'evil' - and therefore what I believe defines 'monster' - is best observed in the behaviour of many animals and in children (or, sadly, adults) who haven't overcome their 'Id' (again, not that I follow or believe in Freud's philosophy, but this probably is the best way to illustrate what I'm talking about without explaining my philosophy too heavily).

In the context of a fictional setting, is there a difference between a monster and an animal in my eyes? Well, I think that largely depends on whether or not the 'monster' in question has the capacity of free will or higher intelligence, since this would determine whether or not it has the ability to know better and act accordingly to that wisdom.[/hider]