A thin film transistor and a manufacturing method thereof, an array substrate and a manufacturing method thereof, and a display panel are provided. The thin film transistor includes an active layer and a wire grid which is disposed at least on a surface of an active region of the active layer and is made of a conductive material. The active layer includes a source region, a drain region, and the channel region between the source region and the drain region. The wire grid includes a plurality of wire grid sections which are spaced apart from each other, and in a direction from the source region to the drain region, a length of the channel region is longer than a length of the wire grid section.