When I was younger, there was a movie that was on HBO about a man writing a novel about a famous screen actress who threw herself in front of a train. The end of the movie reveals that the actress had been using her daughter to impersonate her and it was the daughter who actually killed herself. It was a really great movie and I have been searching for it forever. If anyone knows the name of it, I would really appreciate it! Thanks!

It's possible that this is a 1978 film by the great Billy Wilder called Fedora, which is based on a story by Thomas Tryon (an actor who also produced the classic Johnny Got His Gun AND wrote the novel upon which the cult fave The Dark Secret of Harvest Home was based). This movie, which obviously riffs on Sunset Boulevard, is in fact narrated by William Holden, and also stars Jose Ferrer, Frances Sternhagen, a young Stephen Collins, Henry Fonda, Arlene Francis in her last movie role, AND Michael York... playing himself.