David Cronenberg's early genre work is typically cited through titles like Videodrome (1983), The Dead Zone (1983), and The Fly (1986). Dead Ringers isn't praised nearly as much as those preceding gems, but, to many of the Canadian filmmaker's devoted fans, it's one of his best movies. It's also based on one of the stranger medical stories you'll ever hear.
Directly inspired by Bari Wood and Jack Geasland's novel Twins, Dead Ringers (more of a horrific psychological drama than straight-up horror) follows twin gynecologists (played by Jeremy Irons) as they battle with drugs, depression, and a bad habit of sharing women.
Wood and Geasland's novel, and, concurrently, Irons' characters in Cronenberg's film, are based on Stewart and Cyril Marcus, real-life twin gynecologists whose dead bodies were found in their New York City apartment in 1975, decomposed. Like the characters in Dead Ringers, the Marcus brothers were addicted to drugs, specifically barbiturates, the same drug that killed Marilyn Monroe.