A display device (1100, 1200, 1300, 1400, 1500) comprising: a substrate; and a plurality of thin film transistors (100, 200, 300, 400, 500, 600, 700,800, 900) on the substrate, wherein each of the plurality of thin film transistors includes an active layer (130, A1, A2) having a channel portion and a gate electrode (150, G1, G2) spaced apart from the active layer, the substrate includes a first area, the gate electrode of the thin film transistor disposed in the first area includes: a first part that at least partially overlaps the channel portion of the active layer; and a second part having a thickness smaller than that of the first part and at least partially overlapping the channel portion of the active layer, and light transmittance of the second part is greater than that of the first part, wherein the substrate further includes a third area distinguished from the first area, a gate electrode of the thin film transistor disposed in the third area includes: a first part that at least partially overlaps the channel portion of the active layer; and a second part having a thickness smaller than the first part and at least partially overlapping the channel portion of the active layer, and the second part of the gate electrode included in the thin film transistor disposed in the third area has a smaller area or a larger thickness than that of the second part of the gate electrode included in the thin film transistor disposed in the first area. a substrate; and a plurality of thin film transistors (100, 200, 300, 400, 500, 600, 700,800, 900) on the substrate, wherein each of the plurality of thin film transistors includes an active layer (130, A1, A2) having a channel portion and a gate electrode (150, G1, G2) spaced apart from the active layer, the substrate includes a first area, the gate electrode of the thin film transistor disposed in the first area includes: a first part that at least partially overlaps the channel portion of the active layer; and a second part having a thickness smaller than that of the first part and at least partially overlapping the channel portion of the active layer, and light transmittance of the second part is greater than that of the first part, wherein the substrate further includes a third area distinguished from the first area, a gate electrode of the thin film transistor disposed in the third area includes: a first part that at least partially overlaps the channel portion of the active layer; and a second part having a thickness smaller than the first part and at least partially overlapping the channel portion of the active layer, and the second part of the gate electrode included in the thin film transistor disposed in the third area has a smaller area or a larger thickness than that of the second part of the gate electrode included in the thin film transistor disposed in the first area. a first part that at least partially overlaps the channel portion of the active layer; and a second part having a thickness smaller than that of the first part and at least partially overlapping the channel portion of the active layer, and light transmittance of the second part is greater than that of the first part, wherein the substrate further includes a third area distinguished from the first area, a gate electrode of the thin film transistor disposed in the third area includes: a first part that at least partially overlaps the channel portion of the active layer; and a second part having a thickness smaller than the first part and at least partially overlapping the channel portion of the active layer, and the second part of the gate electrode included in the thin film transistor disposed in the third area has a smaller area or a larger thickness than that of the second part of the gate electrode included in the thin film transistor disposed in the first area. a first part that at least partially overlaps the channel portion of the active layer; and a second part having a thickness smaller than the first part and at least partially overlapping the channel portion of the active layer, and the second part of the gate electrode included in the thin film transistor disposed in the third area has a smaller area or a larger thickness than that of the second part of the gate electrode included in the thin film transistor disposed in the first area.