Lars Thorwald is the main antagonist of Alfred Hitchcock's 1954 film, Rear Window.
He was portrayed by Raymond Burr.
Not much is known about Thorwald, though it's heavily stated by the film's protagonist, L.B. Jeffries that he didn't get along with his wife as he had seen them constantly arguing. This in turn caused him to finally snap and kill her. Unbeknownst to his wife, he was having an affair with another woman, who would eventually aid him in his plan to get away with her murder. One evening Jeff hears a woman scream "Don't!" and a glass break. Later he is awakened by thunder and sees Thorwald leaving his apartment. Thorwald makes repeated late-night trips carrying his sample case. Jeff notices that Thorwald's wife is gone and sees Thorwald cleaning a large knife and handsaw. Later, Thorwald ties a large trunk with heavy rope and has moving men haul it away. Jeff discusses these observations with his much-younger socialite girlfriend Lisa Fremont and his insurance company home-care nurse Stella, and becomes obsessed with his theory that Thorwald murdered his wife. He explains his theory to his friend Tom Doyle, a New York City Police detective, and asks him to find out whether anyone actually picks up the packing crate. Doyle looks into the situation but finds nothing suspicious, and discovers that "Mrs. Thorwald" picked up the packing crate.
Soon after, a neighbor's dog is found dead, by its neck being broken. When the owner sees the lifeless body of her dog she screams to the courtyard: "You don't know the meaning of the word 'neighbors'. Neighbors like each other, speak to each other, care if anybody lives or dies! But none of you do!" and cries in grief. During the woman's hysterics, the neighbors all rush to their windows to see what has happened, except for Thorwald, whose cigar can be seen glowing as he sits in his dark apartment. Convinced that Thorwald is guilty after all, Jeff has Lisa slip an accusatory note under Thorwald's door so Jeff can watch his reaction when he reads it. Then, as a pretext to get Thorwald away from his apartment, Jeff telephones him and arranges a meeting at a bar. He thinks Thorwald may have buried something in the courtyard flower patch and then killed the dog to keep it from digging it up. When Thorwald leaves, Lisa and Stella dig up the flowers but find nothing.
Lisa then climbs the fire escape to Thorwald's apartment and squeezes in through an open window. When Thorwald returns and grabs Lisa, Jeff calls the police, who arrive in time to save her. With the police present, Jeff sees Lisa with her hands behind her back, wiggling her finger with Mrs. Thorwald's wedding ring on it. Thorwald also sees this, realizes that she is signaling to someone, and notices Jeff across the courtyard.
Jeff phones Doyle, now convinced that Thorwald is guilty of something, and Stella heads for the police station to post bail for Lisa, leaving Jeff alone. He soon realizes that Thorwald is coming to his apartment. When Thorwald enters the apartment and approaches him, Jeff repeatedly sets off his camera flashbulbs, temporarily blinding Thorwald. Thorwald grabs Jeff and pushes him toward the open window as Jeff yells for help. Jeff falls to the ground just as some police officers enter the apartment and others run to catch him. Thorwald confesses to the murder of his wife and the police arrest him.