Hall is the creator of the game Hero Rising, the owner of HALL Industries and the original driving force behind the Omega Defiance. He originally brought the seven scientists together to better humanity- but once they turned evil, he created Hero Rising to find soldiers to battle against them.
Not very much is known about Hall. His parents left him for unkown reasons as a child. He is visited by Aaron Stone on occasion, but the camera angle usually displays something such as the back of his head, from the mouth down, a hand or he is dimmed by surrounding shadows or darkness- however in the episode "In Hall We Trust" a fairly clear view of his face is seen and it is easy to decipher he is a tall, middle aged, African American man. Aaron has never seen him in broad daylight, Hall's reasons for this are for Aaron's own safety, these things were stated in "Chuck And Charlie"- which is when Hall's reluctance to show his face was first addressed in the show. The reason Hall does not display his face is because who ever recognized him would become a threat.
In the episode "Hunt me? Hunt you!", Aaron Stone falls for a young female called Tatianna Caine- whom not only reveals herself as aiding the Omega Defiance, but also as T. Abner Hall's daughter. Nearing the end of the episode, Aaron Stone outwits her and sends her back to Hall. The end of the episode displays Hall watching her on his lap top via web cam, and he has apparently locked her away. More about Hall's family life is yet to be revealed.
However, it seems much about T. Abner Hall is still a mystery- including his identity, although he does reveal himself, when explaining that he created Hero Rising, that he is the best player in the world at Hero Rising. In Mutant Rain Part 2, Aaron and his team earn Hall's full trust and as a sign of this, he exposes his face to them saying he trusts them with who he really is. The first people to see his face are Aaron, Emma, Vas, Ram, Jason and S.T.A.N, but afterwards he remains out of the shadows when visting the imprisoned Elias Powers (really a disguised U) and Damaged, but it is unknown if this is just because they are his prisoners or if he is going to fully emrge from the shadows now.