Ancient Greece - Greek Gods
The big guys
Zeus, Poseidon, and Hades.
Zeus, Poseidon and Hades are the three most known and most powerful gods of them all. The three attacked and killed their father, Kronos. After they killed him, they bet on what they would rule, and then they agreed. Zeus would rule the heavens, while Poseidon ruled the seas. Hades ruled the underworld, and after a while he realized he didn't like it. Hades attacked his father Kronos with the Helm of Darkness, Poseidon with a trident, and Zeus with a lightning bolt.
Zeus
Zeus lives in the heavens and protects it. He wields a lightning bolt to shock his foes. He controls weather, and can change clouds into things.
Poseidon
Poseidon lives deep in the sea and protects sea creatures, from the tiniest zooplankton to the largest sea monsters. He wields a trident which can control waves, whirlpools, and anything else that deals with water.
Hades
Hades is the god of the underworld. He protects the souls living in the River Styx, making sure they don't return to their body. He wields the Helm of Darkness, being guarded by his "pet" or "guard dog" Cerberus.
Life Without these Three Greek Gods
If they didn't exist, according to the Greeks, life would be disastrous, the sea would be uncontrollable, with many seamen dying. Without the god of the underworld, souls would be able to go back to their body, making them live to be at least 1,000 years old. And without the god of the weather and the heavens, there would be lots of storms, tornadoes, tsunamis, water spouts, and so much more natural disasters that come from the clouds.