T'ien is a non-canon character that made his first and only appearance in Mortal Kombat novel.
He was the first of the gods, forged from the 'soul' of P'an Ku. He is described as having six arms and four legs.
Simply by the act of thinking of it, T'ien created the other gods (Raiden, Kuan Lin, Shang Ti, Yu, etc.) It was the other gods that he created who eventually became bored and created mortals.
T'ien's holy place is said to be a mountain - Mt. Ifukube in the region of Guangdong in Southeastern China, to be precise.