Stories with similar themes
Sommersby is based on the French film The Return of Martin Guerre, which is based on the true story of Martin Guerre.
The same basic theme was used in a 1997 episode of The Simpsons, "The Principal and the Pauper," when it turns out that Principal Seymour Skinner is actually Armin Tamzarian (a delinquent orphan from New Orleans) who assumed the identity of Sergeant Seymour Skinner when the latter was missing and assumed dead. When the real Seymour Skinner returns home, the townspeople turn against him, discovering that for all of his faults, Armin Tamzarian is actually a better "Seymour Skinner" than the real one. The episode's working title was "Skinnersby", in reference to the film.
In the 1946 British war drama The Captive Heart, the protagonist, a Czechoslovak army captain (played by Michael Redgrave), assumes the identity of a dead British officer in hopes of avoiding being returned to Dachau concentration camp.
The 1957 film The Bridge on the River Kwai has a protagonist (played by William Holden) who has assumed the rank of his dead commanding officer in the hope of receiving better treatment as a prisoner of war.
In Libel (a 1935 play and 1959 film), Sir Mark Loddon is accused of being an imposter by Buckenham, with whom he was a POW during the war. They had shared quarters with Wellney, who had borne a resemblance to Loddon and at times pretended to be him. Buckenham alleges that Loddon is in fact Wellney impersonating the baronet. Loddon sues for libel, but his case is hampered by memory loss, so that his wife, and even Loddon himself, start to doubt his identity.
In Mad Men, Richard "Dick" Whitman goes to war in Korea and his commanding officer Lt. Donald "Don" Draper is killed in an artillery barrage. With his body charred beyond recognition, Whitman switches dog tags with Draper and assumes his identity. The widow of the real Don Draper, Anna Draper, hunts him down, believing Don has run out on her. Instead, she discovers the switch, becoming a very close friend of the fake Don Draper.
In the final minutes of the Family Guy episode "Thanksgiving", another man claiming to be the real Kevin Swanson bursts in the door, claiming the other Kevin (who returned from the war after having been declared dead) is an impostor.
In season 2 episode 6 of Downton Abbey, a soldier returns from war to convalesce at Downton Abbey, which has been turned into a nursing home for wounded officers; the soldier reveals that he is actually Patrick Crawley, the heir to Downton, who was believed to have died on the Titanic. The soldier claims to have been saved from drowning, but to have suffered from amnesia until the war. He tries to start a romance with Edith, who had formerly been in love with Patrick, but the family discovers that he may be an imposter, someone who had worked with Patrick and known him well. He leaves before his identity can be established.
In the 1955 short story "Human Is" by Philip K. Dick, a wife is in a loveless marriage with a scientist. When he returns from a mission he is uncharacteristically kind to her. He is later arrested under the assumption that he is truly an imposter. The story was adapted in the science fiction anthology series Electric Dreams.