In the historical Vedic religion, Indra is a storm god who is king of the devas. He is also a god of order, and he slew Vritra with his weapon the Vajra (thunderbolt). As the Vedic religion developed into Hinduism, Indra's importance declined greatly.
According to the Puranas, Indra is not the god's name but a title. He is portrayed somewhat more negatively compared to in the Vedas.
In Buddhism, Indra is usually called Śakra, and he is king of the devas like in the Vedas.
Origin: India - The Hindu god of rain and thunderstorms. He is known as a war god who wields a thunderbolt known as Vajra. He rides the white elephant Airavata and defeated Vritra, who was causing a drought. He was later embraced by Buddhism and became Sakra, the leader of the four Devas.
なお、仏教においては、『ゾウチョウテン』ら四天王を束ねる帝釈天ともされる。Translation: The thunderbolt god from the ancient Indian scriptures, the Rig Vega. He rides a two-headed golden chariot or elephant, accompanied by "Maruts," the god of storms and rain. He is said to have loved the sacred wine Soma and went around exterminating those who harmed people with his vajra, a vajra hammer. He was also called "Vritrahan" after the poisonous dragon he slayed at that time. In the ancient Indian epic Ramayana, he appears as a sky god and lends his power to the hero Rama, an offshoot of Vishnu. The arrow shot by this power was called "Indra's arrow" and was said to have defeated the army of "Ravana," the king of Rakshasa, who was his adversary. In Buddhism, he is also known as Taishakuten, the leader of the Four Heavenly Kings, including Zouchouten.