King of the devas; most-invoked Vedic deity, with roughly 250 Ṛgvedic hymns addressed to him — more than any other figure. Slayer of the dragon Vṛtra (Ṛgveda 1.32), releaser of the cosmic waters. Wielder of the vajra. Father of Arjuna in the Mahabharata; in Vana Parva 308 disguises himself as a brahmin to extract Karṇa's divine armor (kavacha) and earrings (kuṇḍala) to protect Arjuna — a structurally critical and morally fraught episode that sets up the Kurukshetra denouement.
Ṛgveda passim (the most-invoked Vedic deity, ~250 hymns); Mahabharata Adi Parva 122-123; Vana Parva 308 (Karṇa's kavacha-kuṇḍala extraction); Bhāgavata Purāṇa