Why did Mary Shelly change the name from The Modern Prometheus to Frankenstein? What is the connection between the two?
Mary Shelley's novel was originally titled Frankenstein; or The Modern Prometheus. Shelley apparently never intended the title to be changed or altered; however, many modern publishers have dropped the Modern Prometheus subtitle completely, only referring to it in the introduction. Shelley probably included the subtitle as a "warning against the expansion of man in the Industrial Revolution."
In mythology, Prometheus was the Titan who created mankind by combining clay and water--a crime against the laws of nature. Additionally, Prometheus secretly stole the sacred fire of Zeus and gave it to man. Zeus punished Prometheus by chaining him to a rock and sending a bird to eat his liver each day. The liver would grow back, only to be eaten again by the bird before Hercules killed it, thereby freeing Prometheus.
Symbolically, Victor Frankenstein is the modern Prometheus, who creates mankind in an unnatural manner and is then punished for his act.
Incidentally, the term "Modern Prometheus" was originally used to describe the then revolutionary experiments with electricity being performed by Benjamin Franklin.