intrusive thoughts

Sometimes when my mind is idle, I tend to have these thoughts of unpleasant or horrible things I could do to other people. Sometimes they even appear out of nowhere. These are things I would never do and I deeply dislike even thinking about them, but they always come out of nowhere, as if someone else were whispering them into my mind. I hate thinking these things; it makes me feel like a terrible person despite knowing I would NEVER do anything like that.

Does this happen to anyone else? I really want to know what it is because I can't believe I'm just a bad person.