Constantine IV (, ) (c. 652 – 14 September 685), sometimes incorrectly called
Pogonatos, "the Bearded", out of confusion with his father, was
Byzantine Emperor from 668 to 685. His reign saw the first serious check to nearly 50 years of uninterrupted
Islamic expansion, while his calling of the
Sixth Ecumenical Council saw the end of the
monothelitism controversy in the
Byzantine Empire.