There are the famous monkeys of the Ramayana, for example: Hanuman, Vali, Sugriva, and Angada. Other animal allies of Rama include the birds Jatayu and Sampati, the bear Jambavan, and even the little squirrels, too.
In his earliest incarnations, Vishnu came to earth in the form of animal avatars: Matsya the fish, Kurma the tortoise, Varaha the boar, and Narasimha, who was half-man and half-lion.
Many of the gods also have vahanas, animal vehicles that they ride. Some of the most famous of the vahanas of the gods are Garuda the eagle, Nandi the bull, and Airavata the elephant.
You might also want to look at the great snakes called nagas such as Shesha, Takshaka, Ulupi, Karkotaka and Vasuki.
(Vishnu in the form of Varaha the boar
battles demons and saves the world)