Otis (Giant)

Otis (Ancient Greek: Ὦτος) was a giant son of Iphimedia, wife of Aloeus, by Poseidon. He and his brother Ephialtes were brought back to life by the earth goddess Gaea in The Heroes of Olympus.

The Mark of Athena
Prior to the events of the book In The Son of Neptune, the twin giants had kidnapped Nico di Angelo. They hold the demigod prisoner in a bronze jar, similar to what they did to Ares in the original myth.