First picture is definitely fake - the eyes are whited out, which generally is a give away for trying to hide a camera flash.
Second is hard to tell, but I'd guess fake just because I've never seen something that "weird," though the brightness on the head and the ass make it a bit more suspect. :p
Third is definitely a photoshop.
Alligator man I think has also been proven to be a fake, much like the Mermaid at Snopes.