Ostap () is a Ukrainian male given name. It derives from the Greek name Eustathius.

People with this name include:

• Ostap Bender, a fictional character from the Russian novel The Twelve Chairs

• Ostap Dashkevych (ca. 1495–1535), commander of the Ukrainian Cossacks

• Ostap Ortwin (1876–1942), Polish journalist

• Ostap Steckiw (1924–2001), Polish-born Canadian soccer player

• Ostap Veresai (1803–1890), Ukrainian minstrel

• Ostap Vyshnya (1889–1956), Ukrainian writer, satirist, and medical official