Karna was born to Kunti through her invocation of the sun god Surya in the Mahabharata.
Before her marriage, Kunti received a mantra that allowed her to summon a deity and have a child by him. She tested it by invoking Surya, who fathered Karna. The infant was born with natural armor and earrings, known as kavacha and kundala, which helped mark him as extraordinary.
Kunti placed the newborn Karna in a basket and set him afloat on a river. He was found and raised by the charioteer Adhiratha and his wife Radha, so Karna grew up separated from his royal birth family. Later, he became a close ally of Duryodhana and fought against the Pandavas.
A major tragedy of the epic is that Karna is Kunti’s eldest son and therefore the Pandavas’ half-brother, a truth revealed only after years of conflict.