Question: why was eklavya killed by krishna?
Answer: Eklavya is called as one of the foremost of kings in the Rajasuya Yagya where he honours Yudhishthira by offering shoes with respect. Though he didn't have his right thumb, he was noted as a very powerful archer and warrior. He was killed by Shri Krishna when he tried to attack Dwaraka and the Yadavas.