Mary Shelly had nothing to do with it. Aliens come to earth to snatch women in bikinis for breeding stock.
Directed by Robert Gaffney. Starring James Karen and Marilyn Hanold
(I couldn"t manage to create an embed for this page. This is actually a link to another site.)
Marilyn Hanold (Princess Marcuzan) as an earthling. Playboy, June 1959