Which Greek myth figure is referenced in Frankenstein's subtitle?

The Greek myth figure referenced in Frankenstein's subtitle is Prometheus. Mary Shelley's novel was published as Frankenstein; or, The Modern Prometheus, linking Victor Frankenstein to the ancient figure who stole fire from the gods and gave it to humanity.

In Greek mythology, Prometheus is punished by Zeus for this act: he is chained to a rock, where an eagle repeatedly eats his liver. The organ regenerates, making the punishment perpetual. Shelley's subtitle points to Victor's attempt to seize a godlike power—the creation of life—and suggests that his ambition may bring suffering rather than progress.

The subtitle also distinguishes Victor from the creature. Frankenstein is the scientist who performs the experiment, while the creature is his creation. A common mix-up is to call the creature “Frankenstein,” although the name properly belongs to Victor.

Shelley's novel appeared anonymously in 1818. The Prometheus reference became part of its enduring interpretation as a warning about scientific ambition, responsibility, and the consequences of pursuing knowledge without considering its human cost.