Provided is a thin film transistor and thin film transistor panel array. The thin film transistor includes: a substrate; a gate electrode disposed on the substrate; a semiconductor layer disposed on the substrate and partially overlapping with the gate electrode; a source electrode and a drain electrode spaced apart from each other with respect to a channel region of the semiconductor layer; an insulating layer disposed between the gate electrode and the semiconductor layer; and a barrier layer disposed between the semiconductor layer and the source electrode and between the semiconductor layer and the drain electrode, in which the barrier layer comprises graphene. An ohmic contact is provided based on the type of material used for the semiconductor layer.