A thin film transistor (TFT) array panel effectively minimizing light leakage current and a liquid crystal display including the same. The panel includes a transistor structure having a gate electrode formed on an insulating substrate; a semiconductor layer formed on and insulated from the gate electrode; a light blocking layer formed around and overlapping a portion of the gate electrode; a data line intersecting the gate line to form a source electrode, which overlaps a portion of the semiconductor layer; a drain electrode opposing to the source electrode and overlapping a portion of the semiconductor layer, and a pixel electrode formed on and insulated from the transistor structure and electrically connected to the drain electrode.