Susan Thomas is one of the two main protagonists in the 1985 comedy film Desperately Seeking Susan.
She is portrayed by Madonna.
Susan Thomas is a woman who is from New York City and has an on and off relationship with a man named Jim Dandy, who is a musician and good friends with Dez. Susan is a woman who is wild at heart and has been known to pull a few schemes. While at a hotel in Atlantic City, Susan reads a New York City tabloid with a message from Jim called "Desperately Seeking Susan", Susan reads the ad after a tryst with mobster Bruce Meeker. She steals a pair of ornate Egyptian earrings from his coat before departing; the sinister Wayne Nolan notices Susan's embellished tuxedo jacket as she leaves. Arriving in New York City, Susan dons one of the earrings, stashing the other in her suitcase in a Port Authority locker. She asks to stay with her friend Crystal, a magician's assistant at the Magic Club, and learns Meeker was killed at the hotel.
Susan goes to New York City to meet up with Jim before he goes to Buffalo with his band. Susan goes to a vintage store, unaware she is being followed by Roberta Glass, a woman who is fascinated by the "Desperately Seeking Susan" ads in the tabloid. Susan trades in her jacket and Roberta ends up buying it with the key. Finding Susan's locker key, she posts another “Desperately Seeking Susan” ad to meet with her to return it. Concerned about the ad and Susan's connection to Meeker's death, Jim asks his friend Dez to check on her.
Waiting for Susan at Battery Park and wearing her jacket, Roberta is accosted by Nolan, mistaking her for Susan. Susan spots Roberta, but is arrested for not paying her cab fare. Dez arrives and rescues Roberta, who hits her head and loses her memory. Also mistaking Roberta for Susan, Dez takes her to the Port Authority to collect Susan's suitcase, finding the other earring, and lets her stay at his apartment.
Susan later meets Gary Glass, Roberta's husband who is looking for his wife. Susan, who believes Roberta and Dez are connected to Meeker's death and want to frame her. Susan accompanies Gary home, where they get high. Roberta calls from jail, but hangs up when Susan and Gary answer. After calling Dez to bail her out, they find his apartment ransacked by Nolan, and sleep together.
At Gary's house, Susan sees a TV report about Meeker and Nolan having stolen the earrings, once belonging to Nefertiti. She realizes the truth from Roberta's diary, and posts an ad to meet her at the Magic Club. Dez attacks an intruder in his apartment who turns out to be Jim, and confesses to his relationship with “Susan” as Roberta slips away. She reads the ad, as do Jim and Dez; they arrive at the Magic Club, along with Gary, his sister Leslie, and Nolan. They see Roberta, who now has her memory back performing on stage with Ian the magician.
During her act, Roberta recognizes Nolan, who flees backstage. Dez leaves as Roberta tries to explain the events of her disappearance to Gary, finally voicing her unhappiness and ending their marriage. Nolan threatens Susan at gunpoint, but is knocked out by Roberta.
Later, Roberta finds Dez at work in a theater projection booth. She “introduces” herself and they kiss, as Jim and Susan reunite in the theater below. A final newspaper headline reveals that Roberta and Susan returned the earrings, they both receive a reward for the earrings being returned.