A cyclops is a giant from Greek mythology with a single, large eye in the middle of its forehead. The most famous cyclops appears in Homer's ancient epic poem The Odyssey, where the hero Odysseus becomes trapped in the cave of Polyphemus, a fierce cyclops who tends sheep and attacks several of Odysseus's crew members.

The Greeks imagined cyclopes (the plural form) as enormous, powerful beings who lived in caves and worked as blacksmiths for the gods. According to myth, they forged Zeus's thunderbolts and other magical weapons in their underground workshops. With just one eye, they had limited depth perception, which clever heroes like Odysseus could use to their advantage.

Today, people use cyclops to describe anything with a single eye-like feature. A one-eyed monster in a video game might be called a cyclops. Scientists even named a real type of tiny water creature a cyclops because it has a single eyespot in the center of its transparent body.