There are provided a method of manufacturing a thin film transistor and a display including a thin film transistor.The method of manufacturing a thin film transistor includes forming a barrier layer cm a substrate, forming a semiconductor layer on the barrier layer, forming a gate insulating layer on the semiconductor layer, forming a gate electrode on the gate insulating layer, forming an offset region on an external surface of the gate electrode through a plasma heat treatment process or an annealing process, etching, an offset region of the gate electrode, etching a gate insulating layer except for a portion of the gate insulating layer, positioned below the gate electrode, forming an interlayer insulating layer on the gate electrode, and etching, the interlayer insulating layer to form a source electrode and a drain electrode.