Greek Church of the Holy Trinity (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".

The cathedral was inaugurated on December 21, 1858.
It is built in a Byzantine style, but was added to by Theophil von Hansen who usually designed buildings in a classical Nordic style.