A thin-film transistor (TFT) and a method of manufacturing the same are disclosed herein. The TFT may include a gate electrode disposed on an insulating substrate, an insulating layer disposed on the insulating substrate and the gate electrode, an active layer pattern disposed on the insulating layer to overlap the gate electrode, a source electrode disposed on the insulating layer and at least part of which overlaps the active layer pattern, and a drain electrode which is separated from the source electrode and at least part of which overlaps the active layer pattern. A first ohmic contact layer pattern may be disposed between the active layer pattern and the source electrode and between the active layer pattern and the drain electrode. The first ohmic contact layer may have higher nitrogen content on its surface than in other portions of the first ohmic contact layer.