Did you watch Godzilla right before bedtime? A lot of our unknown creatures come from visual images out of horror films. However, they may possess power or destructive potential that hits at the core of our being. In these cases, we are confronted by a sense of angst or loss from unknown dangers through these creatures.
There are some mixed creatures that are more playful, however. These creatures may be combined characterization of favored friends or pets, or may come from favorite literature or mythology images. In this case, the images are positive for us.