Karna was the eldest son of Kunti (and spiritual son of Lord Surya). She abandoned him when he was just a few days old
Karna became a competent warrior of extraordinary abilities but was denied training by Dronacharya as he was not a Kshatriya
Karna was cursed by Parashurama to forget all the essential knowledge of weapons when he would need them the most, when he found out that Karna had disguised as a Brahmin
Karna shot the fish before Arjuna at Draupadi’s Swayamvara. However, Draupadi rejected Karna since he belonged to a low caste
Duryodhana had nominated Karna as the commander-in-chief in the Kurukshetra War.
However, Bhisma refused to fight under Karna as he was not a Kshatriya.
Karna had to wait until Bhisma fell so that he could take part in the Kurukshetra battle.
Karna had an impenetrable armor attached to his body. Indra made him rip out armor to give Pandavas an edge in the war
Karna had also promised Kunti that he will kill only Arjuna in the war
When Arjuna's Chariot's wheel was stuck in mud, Karna did not attack him. But when Karna's Chariot's wheel was stuck, Arjuna attacked him
To read in detail the curses that led to death of Karna, swipe up the link below.