Mary Shelley (1797-1851) was the daughter of the philosopher William Godwin, who disowned her when she eloped with the married man and poet Percy Bysshe Shelley. They married after the suicide of his first wife. It was their friend Lord Byron, with whom the couple spent a summer in Switzerland, who suggested that she and Percy each write a horror story. Frankenstein was the result, inspired by a nightmare Shelley had when she was eighteen years old and published by the time she was twenty-one.