The Ceryneian Hind in Greek mythology was a huge female deer which lived in the region of Keryneia. It was a sacred animal to the goddess of the hunt Artemis. Although female, it had male-like antlers, which were made of gold, while its hooves were made of bronze. It had the ability to outrun a flying arrow.
Capturing the Ceryneian Hind was the third task that King Eurystheus asked the demigod hero Heracles to complete in the story of the Labours of Heracles. As the hind was unnaturally fast, he believed it would be impossible for the hero to catch. At the same time, he thought that catching the sacred animal would trigger the wrath of Artemis against Heracles and would kill him.
Heracles chased the hind for a whole year in various lands in and out of Greece. There are many versions of how he finally managed to capture it; one has it that he captured it while it slept after lightly hurting it using a trap net. Another version says that Artemis appeared in front of the hero and told him to leave the hind alone; he should then go back and tell Eurystheus what had happened and the task would be considered fulfilled. A different account says that Heracles captured the animal using an arrow between its legs.
After catching the animal and on his way to Eurystheus, Heracles came across Artemis and her twin brother Apollo. He begged Artemis for forgiveness and told her why he was forced to capture the animal. Artemis indeed accepted his apology and forgave him, as long as he would set the animal free. Heracles accepted. When he went to the court of Eurystheus, he found out that the king's plan was to add the animal to his personal menagerie. So, Heracles devised a plan. He said that Eurystheus himself should come to take the animal from him. The king started walking towards Heracles and the hind, but Heracles purposefully left the hind loose a moment too early; the deer escaped with its unnatural speed and went back to its goddess. Heracles then said that Eurystheus simply had not been fast enough.