The Palace of Boukoleon (Greek: Βουκολέων) or Bucoleon was one of the Byzantine palaces in Constantinople (present-day Istanbul in Turkey.) It was probably built by Theodosius II in the 5th century. The palace is located on the shore of the Sea of Marmara, to the south of the Hippodrome and east of the Little Hagia Sophia.
Hormisdas is an earlier name of the place. The name Bucoleon was probably attributed after the end of the 6th century under Justinian I, when the small harbour in front of the palace, which is now filled, was constructed. According to tradition, a statue featuring a bull and a lion stood there, giving the port its name (βοῦς and λέων are Greek for "bull" and "lion" respectively). "House of Hormisdas" and "House of Justinian" are other names referring to Bucoleon Palace.
Emperor Theophilos, among his other works, rebuilt and expanded the palace, adding a large façade on top of the seaward walls. The ruins suggest a balcony looking out to the sea was present, accessible through three marble-framed doorways, still visible today.