A TFT array substrate, OLED display including the same, and a manufacturing method of the OLED display are disclosed. In one aspect, the TFT array substrate includes a substrate and a TFT formed over the substrate. The TFT includes an active layer, a gate electrode, a source electrode, a drain electrode, a first insulating layer interposed between the gate electrode and the source and drain electrodes. Each of the source and drain electrodes is interposed between the active layer and the first insulating layer. The TFT array substrate also includes a capacitor formed over the substrate and having lower and upper electrodes and a pixel electrode electrically connected to the TFT.