A thin film transistor (TFT), a method for fabricating a TFT, an array substrate for a display device having a TFT, and a method for fabricating the same are provided. An oxide thin film transistor (TFT) includes: a gate electrode formed on a substrate; a gate insulating layer formed on the gate electrode; an active layer formed on the gate insulating layer above the gate electrode; an etch stop layer pattern formed on the active layer; a source alignment element and a drain alignment element formed on the etch stop layer pattern and spaced apart from one another; and a source electrode in contact with the source alignment element and the active layer and a drain electrode in contact with the drain alignment element and the active layer.