A thin film transistor includes a semiconductor which is disposed on a substrate and includes a source region, a drain region and a channel region, a gate insulating layer disposed on the semiconductor, a gate electrode disposed on the gate insulating layer, an interlayer insulating layer disposed on the gate electrode, contact holes defined in the interlayer insulating layer, the contact holes respectively exposing the source region and the drain region of the semiconductor, and a source electrode and a drain electrode which are disposed on the interlayer insulating layer and respectively contact the source region and the drain region through the contact holes, where at least one of the contact holes exposing the source region and the drain region obliquely traverses the semiconductor.