The characters in The Haunting of Hill House are all well-realized types, with Eleanor Vance the most developed, rounded character. Eleanor, thirty-two, has spent most of her adult life caring for her invalid mother, and she is shy, repressed, and looking for her identity. She comes to the attention of Dr. Montague because of a much-publicized poltergeist incident her family was involved in when she was twelve. In context the idea develops that the falling stones from the poltergeist are generated from the repressed hatred in Eleanor. Eleanor's psychic sensitivity makes her, in Jackson's words, a "vehicle for every kind of fear." Eleanor is looking for a home, in the truest sense of the word, since her own childhood and youth caused her to feel a stranger among her own family and familiar surroundings. Her fatal summer stay at Hill House proves to be her quest for a home, so that she becomes another one of the ghosts at the novel's end.

The rest of the cast supplements the story that ends up featuring Eleanor's failed quest. Dr. Montague is a genial academic authority figure, a favorite kind of character in Jackson's fiction. The problem with Dr. Montague is the single problem of the entire ghost party, Eleanor included: Dr. Montague, in setting up the ghost hunt, attempts to study rationally matter fundamentally irrational; also, with the kind of deep, spiritual journey the project involves, he, like the rest of the group, cannot avoid appearing to be a dabbler. Theodora provides a clear, emphatic foil to Eleanor, since she is decidedly flamboyant, attractive, bohemian, and unrepressed. And Luke Sanderson, a young wastrel, is along for the ride. Similar to Theodora in several strains of his character, less straight-laced than Dr. Montague or Eleanor, he provides comic relief, as something of the glib seducer who appears at times in the Jackson canon.

All these characters encounter the house, itself a kind of character since it is such a dominant setting, alive and moving with ghosts and unexplained, negative activity.