psychopath

"That dog acts like a little psychopath when it chases its tail"

"I felt a chill run down my spine when I realized the charming stranger might be a psychopath"

"Is it possible for a psychopath to feel genuine remorse for their actions?"

"The movie villain was a clever psychopath who outsmarted everyone"

"Stay away from that man; he's a known psychopath who cannot be trusted"