Apollo is the most widely worshiped god next to Zeus. He never married and was the god of many things. Apollo was originally the god of shepherds, but is also the god of music, poetry, archery, healing, prophecy, purification, and seafaring. He is also the sun god. He is usually seen with a bow or a lyre.
Poseidon is the god of the sea. He is one of the Olympian gods. He is the son of Cronusand Rhea. He is the brother of Hades, Zeus, Demeter, Hera and Hestia. His wife is Amphitrite. Although Poseidon is the best known sea god, in ancient times he was the god of herdsmen. In those times he even came before Zeus. His emblem is the trident. He is the father is Triton.
Hades was the god of the Underworld. He had little mercy and did not like to allow any souls, living or dead, to exit the Underworld. Hades was very gloomy. Hades also had many riches, which were stored in the Underworld. He had a "Cap of Darkness" which many heroes asked to borrow because it made the wearer invisible.