A thin film transistor showing desirable contact characteristics during contact with indium tin oxide (ITO) or indium zinc oxide (IZO), in which a first conductive pattern including a gate electrode and a second conductive pattern including a source electrode and a drain electrode are formed without an etching process, a TFT substrate including the TFTs, and a method of manufacturing the same. The thin film transistor includes a gate electrode formed of a first conductive layer, a gate insulating layer covering the gate electrode, a semiconductor layer forming a channel on the gate insulating layer; an ohmic contact layer formed on the semiconductor layer, and a source electrode and a drain electrode formed of a second conductive layer and of a third conductive layer. The second conductive layer includes an aluminum-nickel alloy and nitrogen and is formed on the semiconductor layer. The third conductive layer includes an aluminum-nickel alloy and is formed on the second conductive layer.