A thin film transistor (TFT), a method of fabricating the same, and an organic light emitting diode (OLED) display device including the TFT. The TFT includes a substrate having a pixel region and a non-pixel region, a semiconductor layer, a gate insulating layer, a gate electrode, and source and drain electrodes disposed on the pixel region, at least one gettering site disposed on the non-pixel region, and at least one connection portion to connect the at least one gettering site and the semiconductor layer. The method of fabricating the TFT includes patterning a polycrystalline silicon (poly-Si) layer to form a plurality of semiconductor layers, connection portions, and at least one gettering site, the semiconductor layers being connected to the at least one gettering site via the connection portions, and annealing the substrate to getter the plurality of semiconductor layers.