Indian Mythology
Reincarnation
In Hinduism a common belief that is shared by most people is the belief in reincarnation. People believe that you will be reincarnated again and again until you reach moksha or nirvana, the ultimate spiritual goal when you will finally be released. The ideas of reaching Nirvana and gaining release is one of the main focuses of Buddhism but it was originally a Hindu belief. In many Hindu epics, in times of need Shiva and Vishnu would create an incarnation of themselves to help.
Karma
Karma is probably the most well known belief in Hinduism and even people who know nothing about Hinduism have heard of or have this belief. It is the belief that doing good things means that good things will come to you but if you do bad things the same applies. It is where the saying "What comes around goes around" is derived from. This belief is shown many times in Hindu tales, like when someone uses evil ways to get what they want it always comes back to bite them, usually in the form of divine punishment.