The Erymanthian Boar was a fearsome animal in Greek mythology. Capturing it alive was one of the tasks that King Eurystheus asked the demigod hero Heracles to complete during the story of the Labours of Heracles.
The boar was a giant creature living on Mount Erymanthos, a region sacred to the goddess of hunt Artemis. When the boar would reach the farmlands, it would lay waste and destroy everything in its passing. The capturing of such a fearsome animal was not an easy task, and this is why Eurystheus chose it as the fourth labour of Heracles.
The hero set forth and initially visited a centaur who was a friend of his; his name was Pholus. The two friends had lunch and then decided to open a jar of wine; after opening it, the smell attracted all the centaurs of the mountain. They all started drinking, not realising that the wine should be mixed with water first, as was customary in ancient Greece. So, they became drunk and started attacking. Heracles shot poisonous arrows against them and the drunken centaurs retreated. Pholus was curious as to why the arrows were fatal, and while examining one, he also got poisoned. According to one account, an arrow also mistakenly hit the centaur Chiron, who, although immortal, was still able to feel the pain. So, he asked the gods to lose his immortality, and replace the Titan Prometheus who was chained on a mountain top where an eagle ate his liver daily. So it happened, and the eagle continued to eat Chiron's liver until it was shot down by Heracles.
Heracles then asked Chiron how to catch the boar; Chiron said that he should lure it into thick snow, thus making it difficult for the animal to move. Heracles followed the centaur's advice and managed to capture the animal. He then took it back to the court of Eurystheus, who upon seeing it, was so scared that he hid inside a huge jar and asked Heracles to get rid of it.
See Also: Labours of Heracles, Heracles, Artemis, Eurystheus, Chiron, Prometheus