 Mary Shelley wrote one other science fiction book published in 1818. It involves a worldwide plague that leaves only one survivor. It's not particularly good. It ends in the year 2100, which looks exactly like the early 18th century. The one thing that critics of the time found most laughable about the book, it was a subplot in which the English monarchy collapsed and became a democracy. The character's life is a thinly disguised biography of her late husband Percy Shelley, so people who are interested in him should give the book a look.