A heterocyclic compound represented by one of Formulae 1-4 below and an organic light-emitting device including an organic layer that includes the heterocyclic compound. The heterocyclic compounds have excellent light-emitting characteristics and excellent electron transporting characteristics, and thus may be used as electron injecting materials or electron transporting materials suitable for all-color fluorescent and phosphorescent devices, such as red, green, blue, and white fluorescent and phosphorescent devices. In particular, the heterocyclic compounds are efficiently used as light-emitting materials of green, blue, and while fluorescent devices. By using the heterocyclic compounds, organic light-emitting devices having high efficiency, low driving voltage, high brightness, and long lifespan may be prepared.