An organic light-emitting display apparatus includes a substrate and an active layer disposed on the substrate. The active layer includes a source region, a drain region, and a channel region disposed between the source region and the drain region. A gate electrode overlaps the channel region. An auxiliary gate electrode is disposed between the gate electrode and the channel region. A first voltage is applied to the auxiliary gate electrode. A first thin-film transistor includes the active layer, the auxiliary gate electrode, and the gate electrode.