Tantalus

Tantalus replaced Chiron as Camp Half-Blood's Director of Activities for a time during The Sea of Monsters when Chiron was suspected of having poisoned Thalia's tree. He did not like the campers and appeared to have particular pleasure in torturing Percy Jackson and his half brother Tyson, but seemed to have a soft spot for Clarisse and was the person who decided to send her on the quest. He also started up chariot racing again and with the rule that if anyone killed anyone, they would have no dessert for a week. Tantalus was banished to the Underworld again after Chiron was reinstated.

While he was at the camp, Mr. D took particular pleasure in watching him try to eat or drink, always unsuccessfully. Dionysus removed his curse after his job was done. However, just before he was banished, he managed to pick up some food, but before he could eat it he was sent back to the Underworld.

History
Tantalus was the king of a city, Tantalis, which was named after him. Zeus offered him a spot at the Olympian's table, but when he went to them he stole nectar and ambrosia, brought it back to his people and revealed the secret of the gods. For doing so, he offered up his son, Pelops as food for the gods. Only Demeter touched the food, because she was distraught about her daughter, Persephone. She didn't know what it was and ate part of the boy's shoulder. Zeus took the parts of the boy, put them together and was able to bring him to life once more. He was given a bronze shoulder by Hephaestus. However, because of the theft, when Tantalus died, his punishment was stand in the middle of a lake under the branches of a fruit tree, but whenever he reached for the fruit, the branches would retreat from his grasp; and whenever he leaned down for a drink, the water would recede from him.