Koca Mustafa Pasha Mosque (Turkish: Koca Mustafa Paşa Camii; also named Sünbül Efendi Camii) is a former Eastern Orthodox church converted into a mosque by the Ottomans, located in Istanbul, Turkey. The church, as the adjoining monastery, was dedicated to Saint Andrew of Crete, and was named Saint Andrew in Krisei or by-the-Judgment (Greek: Μονή του Άγίου Άνδρέου ἐν τῆ Κρίσει, Monē tοu Hagiοu Andreοu en tē Krisei). Although heavily transformed during both the Byzantine and the Ottoman eras, it is one among the few churches in Istanbul still extant, whose foundation goes back to the sixth century.

Location
The building lies in the Istanbul district of Fatih, in the neighborhood of Kocamustafapaşa, along Koca Mustafa Paşa Caddesi. It is placed inside the walled city, and not far from the church of Saint John of Stoudion, on the slopes of the seventh hill of Constantinople near the sea of Marmara.