The Invisible Man invokes both a mood of horror and one of relative confusion or bewilderment. The novel generates horror from the combination of cruelty and power within the Invisible Man himself. The fact that he can easily get away with murder and has no moral qualms about doing so makes him a rather terrifying menace. Indeed, Griffin essentially becomes the equivalent of a vengeful spirit due to his desire to instill a "reign of terror." Griffin's lack of empathy toward his father, the cat, and Mr. Marvel (among others) demonstrates that he is something to be feared. He lacks compassion and humanity, turning him into a force that is not to be reckoned with—and, thereby, something to be feared.
At the same time, the novel is also rather amusing. The concept of an invisible man is, at times, supposed to be funny. Many of the action scenes, in which men emerge unscathed except for a blow to the nose or with messed up clothes, are somewhat silly. The discomfort of certain characters—like Marvel's mouse-like fear of the Invisible Man or Doctor Kemp's anxiety while he pretends to be sympathetic toward Griffin—also has a humorous element to it.
