I don't usually find direct inspiration in dreams or nightmares. I just woke from a nightmare which featured a villain which was so creepy, so, um, nightmarish, that he is just begging to be pulled into the real world. He was so insanely creepy that as soon as he intruded in my otherwise "normal" dream, I lucidly thought, "oh, now this is a nightmare."
Strangely, at some point my dream brain decided that he was no longer a threat and we could be friends. Take that as you will, Dr.