In a word, the characters are stereotypes. Cosmo Topper is a stuffy banker as well as a henpecked husband; Mrs. Topper a shrew and the voice of conventional morality; Marion Kerby a witty and sexually vibrant representative of the flapper era; and her husband George a handsome playboy who uses his wealth only to pursue his own pleasure. The other two ghosts, Colonel Scott and Mrs. Hart, are of the same type, one generation removed. The others are what E. M. Forster called flat or one-dimensional characters: bellhops, police, salespeople, secretaries.

Character bows to situation in Topper, and the situations are always ludicrous and fantastic. All women are potential sex objects, all men potential philanderers. The characters function well in this fun-filled world, but as they move from one Smith novel to another, they tend to become formulaic, interchangeable, and repetitive.