Originally from Hindu mythology, the vajra is the weapon of the thunder god Indra (analagous to Thor's hammer Mjolnir in Norse mythology). It is a small, two-headed club with multiple prongs on each head, and symbolizes both the properties of a diamond (indestructibility) and a thunderbolt (irresistible force). From Hinduism the concept spread, manifesting as a weapon-shaped ritual item used in Tantric and Tibetan branches of Buddhism.
The terms appearing below are subtypes of vajra.