Trivia: In the original ending, Henry Frankenstein dies or is killed before the monster throws him off the windmill.
Trivia: All of the laboratory equipment was later used in Mel Brooks' comedy "Young Frankenstein."
Trivia: Universal Pictures originally wanted Bela Lugosi to play Frankenstein's monster since he had done such a great job playing Count Dracula earlier that year. But Bela turned the role down because he did not want to be 'hidden' under all that make-up. Yet 12 years later, Bela would play Frankenstein's monster in 1943 film 'Frankenstein meets the Wolf Man'.
Trivia: After the movie was released into theaters, some scenes were cut because they were too controversial at the time. Scenes like the little girl drowning after the monster accidentally throws her into the water. Henry Frankenstein's line of "It's Alive. It's Alive. It's Alive. In the name of God, now I know what it feels like to be God." was also cut because it was deemed too blasphemous. Also the scene where the hunchback is torturing the monster with a torch was given the axe, as well as the scene where the monster tries to attack Elizabeth (but only in England). These scenes were added back into the film many years later when the movie was re-released on VHS (and later on DVD).
Trivia: Because he was so unknown when he was cast as The Monster, Boris Karloff was not invited to the film's premiere.
Answer: There seems to be no officially stated reason why the name was changed, but it's possible to theorise. There were numerous changes between the original book and the film. One theory is that these changes were to make the story more accessible to the mass audiences, and altering the name of the main character to a more common one could be seen as part of that. Another (possibly more likely) reason is down to alterations in the characters. Unlike the book, the film ultimately seeks to redeem Frankenstein's character, making him a more human and sympathetic character. Conversely, the character of Frankenstein's old friend, named Victor in the film, but Henry in the book, has been made a much less pleasant character. As Victor is quite a harsh, martial name and Henry comes across as rather more amiable, the filmmakers might well have decided that it would be more appropriate to the characters that they were trying to portray to switch the names round.
Tailkinker