Hey there,
I have had dream "enemies" that do re-occur. Although I have yet to encounter them while lucid, its usually a twisted looking version of myself, or one of my friends; Its essentially the same thing though.

Since I've learned about how the mind works during dreams, I've been picking up on little things to help myself either avoid or be able to confront any imaginary threats during my dreaming. For some reason these tricks are just "programed" in my mind for me to do even if I don't become lucid.

The first thing is to avoid mirrors in dreams. Its silly, but in reflections there is (for me anyway) a high chance of seeing something threatening or distorted. That's usually how I run into that frightening figure. Once I learned I, for some reason, just don't do it anymore in dreams.

The location of the dream plays a big part too. When a dream takes place in my room, I know to not look at the mirror. I have a strange, leafless forest the appears many times in my dreams too. I haven't seen anything yet, but I often get a feeling a distress or that something bad is getting close when I'm there. By knowing locations you can try to prepare yourself ahead of time.

Another thing that I've done that could help bail you out of trouble in general is by telling yourself that you have the ability to defend yourself in your dreams. I now keep an imaginary "sword" of sorts now in my dreams when I become lucid, just in case I run into trouble and can't think straight enough to use my mind to warp myself somewhere else.

I hope that this helps you deal with your dream monsters somehow!!