Lee Chaolan was introduced in the original Tekken and has been in every game, except Tekken 3. Lee Chaolan is the adopted son of Heihachi Mishima.
Lee is Kazuya's stage 8 sub-boss. When you beat arcade mode with Kazuya, Lee will be unlocked and when you use Lee in Arcade, Kazuya will be Lee's stage 8 sub-boss, this is for the console version only.
Lee's parents died when he was a very young , this left him to fending for himself on the streets. While living in a bad environment each and every day, he quickly became a skilled scrapper, they improved his reflexes, this was amazing for a boy of his age. These great qualities is what caught the eye of Heihachi, who watched as Lee fought off several other kids while on a business trip. Heihachi decided to adopt Lee because he was impressed by his street fighting skills. Heihachi then took Lee Chaolan back to Japan for a better education. Heihachi never actually felt any emotion towards Lee, his main real purpose was to give Kazuya a rival to inspire him to become stronger. Their combat skill is equal, and the people who have heard of his power fear the "Silver-Haired Demon".