The book says the affair ended when Reeve discovered Culver was a porn star, according to the Daily Mail.
Culver died of an AIDS-related illness.
Reeve, an actor best known for his movie role as Superman, died in 2004 of heart failure. His death came nearly 10 years after he was paralyzed in a horse-riding accident. He was married to wife Dana for nearly 12 years.
The new Hollywood Babylon series is written by sensationalist biographer Darwin Porter and Danforth Prince.
George Reeves played Superman in the 1950s television series.
