S.Z.
We had a big, giant stuffed dog. It is as long (nose to tail) as their twin bed is wide! I told mine that if a monster, or anything else, came into their room the dog would bark and scare the creature away. It would also wake up mom and dad and we would come to get you. My son still sleeps with it but I think he uses it more like a pillow now and not a "moster attacker". We also did the whole mosters arent real speach but some children have such a vivid imagination that to them, mosters are every bit as real as people. So while it wasnt "encouraged" per say I didnt dismiss them or their feelings about it. Good luck with it! Try to remember they are only little once and this kind of stuff goes away all too soon and you will just be sharing stories of when he was afraid of monsters! I try to think of that every day when my children are doing something that is so obviously ridiculous!
SZ