Ostap is a Ukrainian male given name. Its Russian counterpart is Evstafiy. It is derived from the Greek Eustathius.
Among people with this name are:
- Ostap Bender, a fictional character from the Russian novel The Twelve Chairs.
- Ostap Dashkevych (ca. 1495 - 1535), a commander of the Ukrainian Cossacks.
- Ostap Ortwin, Polish journalist
- Ostap Steckiw, a Canadian soccer player from Lviv
- Ostap Veresai (1803-1890), a Ukrainian minstrel.