There are 15 enemies that you can make fat - the ones that you mentioned aren't enemies so you can't do anything like that with them
Soo...
The Kobold, The Gator, The Werewolf, The T-Rex, the kangaroo, the Naga, the Bat, the fox, the Komodo rogue, the Komodo jock, the... Ghost/Incrementum(?), the turtle and the shark are the ones I believe you can find in normal play. While the robot and the slug require certain curses.
My goodness, so many characters.