Holy Trinity Greek Orthodox Church (Griechenkirche zur Heiligen Dreifaltigkeit) is a Greek Orthodox Church Cathedral in the first district of Vienna, Austria, in the historic Greek neighborhood of Vienna's Innere Stadt. The neighborhood has also been known as the "Fleischmarkt".
Since 1963 the cathedral has been the seat of the Greek Orthodox Metropolis of Austria (the Ecumenical Patriarchate of Constantinople: the Metropolis of Austria and Exarchate of Hungary and Middle Europe).