John "Scottie" Ferguson
Scottie is an independently wealthy detective working in San Francisco whose career is interrupted by a traumatizing instance of vertigo. He soon becomes involved in an unusual case following an old acquaintance's wife, and ends up falling in love with her. He is passionate and wants to do the right thing, but is haunted by his fear of heights and his sense of guilt about the deaths of those close to him. His mental disturbances lead him to become exceedingly obsessed with creating the woman he has lost, Madeleine, in his new girlfriend, Judy. At the end of the film, he has become aggressive, bullish, and unswerving in his search for the ideal woman.
Madeleine Elster
As we learn in the latter half of the film, "Madeleine" as we know her is actually Judy, a young woman from Salina, Kansas, whom Gavin Elster hired to portray his wife to cover his murder of his actual wife. As Madeleine, Judy is mysterious, ethereal, and racked with delusions and visions about the past that lead her to self-destructive behaviors.
But in reality, Judy Barton is a simple girl looking for opportunity in the big city. She lacks the elegance and social grace of Madeleine, but allows Scottie to transform her into her former image in exchange for love. She worries that Scottie will never love her for who she is, and she ends up being right.
Midge
Midge is an old college friend of Scottie's and his ex-fiancée. In many ways, she is the opposite of Madeleine Elster; she is competent, practical, wise-cracking, and maternal towards Scottie. It is clear that she still harbors romantic feelings towards him, and grows jealous when he falls in love with Madeleine. She tries to use her wit and irony to win Scottie over, but this backfires, resulting in her rejection and humiliation.
Gavin Elster
Gavin is an old acquaintance of Scottie's from college who is now in the shipbuilding business. He hires Scottie to look after his wife, which we learn later is actually just a way to cover for the fact that he has already killed his wife. He uses Scottie's vertigo to ensure that his plot works, and though he appears thoughtful and even-keeled, he is actually manipulative and nefarious.
Pop Leibel
Pop Leibel is a friend of Midge's and the owner of a bookshop. Midge thinks of him as a keeper of San Francisco history and he serves as a resource for Scottie when he is trying to learn more about Carlotta Valdes.
