Ladon

Ladon guarded the golden apples that Gaia gave Hera as a wedding present, in the garden at the western edge of the world. Hera set him there because the Hesperides, the nymphs who tended the tree, had been helping themselves to the fruit. The dragon was the correction.

Sources cannot agree on his parents — Phorkys and Keto in Hesiod, Typhon and Echidna elsewhere — but they agree on the detail that matters: he never slept. Every other guardian in Greek myth has an off-hour. Argus of the hundred eyes closed them in shifts and Hermes talked the rest shut. Ladon has no shift. Apollonius gives him a hundred heads speaking a hundred voices, which is less a description of a body than of a problem with no blind side.

Heracles' eleventh labour was to fetch those apples, and the myths split on how he managed it. In the older version he shoots Ladon over the garden wall and takes the fruit himself. In the version that survives better, he declines to fight at all and sends Atlas — whose daughters the Hesperides were — while he holds up the sky, on the reasoning that the dragon would not attack family. The second version is the more interesting one, because it makes the labour a puzzle rather than a fight.

The Argonauts arrived a day late and found him dying among the roots, still twitching, the nymphs in mourning. Hera set him in the sky afterwards as Draco, which is the standard Greek consolation prize: you lose, and then you are a constellation.