Nothing’s spookier (or more beloved) than a well-imagined monster. Monsters tend to outlive the protagonists they terrorize. Who is Frankenstein without his monster? Or Jonathan Harker without Count Dracula?

Here is one way that an artist used that love of monsters to his own advantage.

In 1597, the master painter Caravaggio was commissioned by an Italian diplomat to create a gift for the Grand Duke of Tuscany. For his subject, Caravaggio chose something rather startling – a portrait of Medusa.

We all know the Greek myth of Medusa – the dreadful Gorgon cursed by Athena to have snakes for hair and a face so horrifying that one glance would turn you into stone. Her face appears repeatedly throughout art history and in today’s culture. We also all know how her story ends. Perseus, son of the Greek god Zeus, decapitated Medusa using a shield given to him by Athena.

In Caravaggio’s portrait, he depicted the exact moment that Medusa was executed by Perseus. Blood streams from her neck as her face freezes in a scream. The snakes on her head seem to reach beyond the painting in as they writhe in pain. Caravaggio used his masterfully dark realism to bring to life an unforgettable portrait of horror.

The most interesting part? Caravaggio actually replaced Medusa’s face with his own. He meant to show that he was immune to her dreadful gaze. He also ensured that his own face would endure throughout history, forever entwined with the monster’s myth. In Medusa’s death, he saw a way to a kind of immortality.

How do we see ourselves in the monsters we love? How do the roles of perceived and perceiver line up with the roles of monster and protagonist? And what are some of your favorite unforgettable monsters?