A method of fabricating a thin film transistor includes forming a substrate having first and second regions, a semiconductor layer pattern formed in the first region and the second region, and a first gate insulating layer pattern formed on a channel region of the semiconductor layer pattern of the first region. A second gate insulating layer is formed on the substrate, a first conductive layer pattern is formed above the channel region of the first region and above the semiconductor layer pattern of the second region, and an inter-layer insulating layer is formed on the substrate. A second conductive layer pattern is formed in the first region and above the first conductive layer pattern of the second region. The second conductive layer pattern of the first region is coupled to the semiconductor layer pattern of the first region through the second gate insulating layer and the inter-layer insulating layer.