Forum user @ColtRosewood found talk about something that may hint at the appearance of the 5th Monster. He found that it talks about a spider-type of Monster with a singular eye. What makes this interesting to me is that upon searching the web one day a couple weeks back I found this:
This is an image of a “Flesh Spider” drawn by a one such “Stephen-0akley” and can but found on his deviant-art page however I found it through Google. What I find interesting is that when I found this I posted it to the forums and some people said that Stephen Oakley is a concept artist for Evolve, so I thought it was amazing that I may have found some T5 Monster concept art however NOW thanks to @ColtRosewood I feel that this may be what the 5th Monster MAY look like, not exactly but heavily inspired.