Vajrapani means one who holds the vajra, a thunderbolt-like weapon in his hand. He is the protector of Buddha and symbolises his power. He is a bodhisattva around the Buddha and also called Vajrasattva. He is thought to be the general of the yakshas as per the Golden Lotus-sutra. He forms a triad along with Bodhisattva Avalokiteswara and Amitabha in some forms of Buddhism.
Vajrapani is mostly depicted with a wrathful,angry expression; holding the vajra in his right hand. He sometimes wears a skull-crown but usually a five-pointed crown representing the five Dhyani Buddhas.
Vajrapani has many forms. He is called Dhyani-Bodhisattva equivalent to Akshobhya. He is referred to as Acharya Vajrapani in his role as Dharmapala with a third eye, a bell and a lasso. He is called Nilambara-Vajrapani when he has one head and four arms and treading on snakes. As Mahachakra-Vajrapani he has three heads , six arms and carrying the vajra and snakes. He is also depicted with the head,wings and claws of Garuda, when he takes this form to protect the nagas who came to worship Lord Buddha from the birds who devour snakes.
In different countries where Buddhism flourished he is seen in different depictions.In Nepal he is white in paintings.In Cambodia he has four arms. In Japan he is seen depicted in mandalas. In Tibet he is seen in many fierce forms. His Indian depictions are many. In Gandhara art he is the protector of the Buddha.He is on one side of the Buddha along with Padmapani on the other at Cave No.1 of Ajanta caves at Aurangabad in Maharashtra.
Vajrapani is believed to rock the mountains with his weapon vajra as mentioned in some Buddhist texts.
Vajrapani,7th century,Ajanta caves, Maharashtra,India.
By Indischer Maler des 7. Jahrhunderts [Public domain], via Wikimedia Commons
Vajrapani, 8th-9th century,Lalitagiri, Odisha.
Vajrapani, wall painting , Caves of the Statues, Kizil, 406-425 AD,Ethnological Museum, Berlin.
By Daderot (Own work) [CC0], via Wikimedia Commons
Vajrapani, 9th century, Tibet,British Museum,UK.
By Anonymus (British Museum) [Public domain], via Wikimedia Commons
Vajrapani, 1731, gilt bronze, Nepal, Norton Simon Museum.
By Wmpearl (Own work) [CC0], via Wikimedia Commons