3. Vishnu the sustainer
Vishnu is the protector of the universe. There are some times when the balance between good and evil gets disturbed. When some evil creature becomes uncontrollably powerful and starts assaulting the good. Whenever that happens Vishnu comes down to the earth in the form of a human or various other creatures in order to protect the good, destroy the evil and reestablish righteousness.
These earthly forms of Vishnu are called Avatars. There are 10 major Avatars of Vishnu including Rama, Krishna, Buddha and Kalki. The last Avatar Kalki is a man with winged white horse. He is yet to appear on this earth. He would end the Kali yuga, the last age marked by spiritual degeneration, so that the universe can restart again.
Vishnu has a dark or pale blue complexion. In four hands he holds a lotus flower, a conch, a mace and a deadly weapon called Sudarshana chakra. Sudarshana chakra is a rapidly spinning disk with sharp teeth at the edge. When Vishnu points it to an enemy, it can go and chop the head off.
Like many other mythologies, Indian mythology has a story about a great flood. Vishnu took the form of a little fish (Matsya Avatar) and asked protection from Manu, the first man. The fish also told him about an upcoming great flood. Manu took the fish under his protection and put it in a jar. When the fish outgrew the jar, Manu transferred it to a tank. As the fish kept growing, it was transferred to the Ganges river and eventually to the ocean. The fish, now a giant in the ocean, advised Manu to build a big ship and save all life forms. When the flood came the fish pulled the ship and steered it to the safety of the Himalayas.
Here is a story of another avatar of Vishnu. Asura Hiranyaksha, the son of Diti, worshipped Brahma for a long time. Pleased by his dedication and reverence, Brahma gave him a boon that no Deva, human or other creature could kill him. Empowered by this boon, Hiranyaksha started tormenting the inhabitants of the earth and fought with the Devas. On a whim he took the whole earth and dived deep under the cosmic ocean. All the distressed Devas came to Vishnu for rescue. Vishnu took the form of a half man and half pig (Varaha Avatar) and dived under the ocean. After a grave battle with Hiranyaksha, the Varaha slew him. Subsequently the earth was brought back to its original place and peace was restored.