Demetrius Zvonimir (d. 20 April 1089) is King of Croatia from 8 October 1076 until his death.

He also rules as Ban of Slavonia (1064–1074), and is named Duke of Croatia in around 1075.

His native name is Zvonimir, while the name Demetrius (Dmitar in Croatian) is adopted at his coronation.

He begins as a Ban of Slavonia in the service of King Stephen I.

Afterwards, he is appointed Duke of Croatia by his predecessor Peter Krešimir IV, who later declares him as his heir.

In 1075, Dmitar Zvonimir succeeds to the Croatian throne.

As a vassal of the Pope, his reign is characterized as relatively peaceful; with no extensive war campaigns, and economic and cultural development.

He is the last native king who exerts any real power over the entire Croatian state, which he inherits at its height and rules from the city of Knin.