Conner Kent aka Superboy.
He was found in CADMUS as a cloning project, to defeat Superman and/or become Superman. He was made from Supermans DNA and force fed information for 16 months. Robin, Aqualad and Kid Flash found him deep inside CADMUS after going on a self assigned mission, one the League did not give them. The rescued him and he joined the Team, made out of the three sidekicks and Ma'gann, the nice of Martian Manhunter. He has anger issues and wants Superman to notice him, and tries to impress him. A few episades before the end of season one, he and Ma'gann started to date. He is also the "son" of Lex Luther, who gave CADMUS his DNA to create Superboy. He has a pet wolf named Wolf, and is loyal to those who has erned his trust.
In season two, he has grown in his own power, and is no longer dating Ma'gann after 4 years of being together. He is experianced and has still remained in the Team, even when he is offered a membership of the League.