The Olentangy River (IPA pronunciation: ) is a tributary of the Scioto River in Ohio.

It was originally called keenhongsheconsepung, a Delaware word literally translated as "stone for your knife stream" based on the shale found along its shores. Early settlers to the region translated this into "Whetstone River." In 1833, the Ohio General Assembly passed legislation intending to restore the original Native American names to some Ohio waterways, but mistakenly gave Whetstone River the name "Olentangy"—Delaware for "river of the red face paint"—which had actually belonged to what is now known as Big Darby Creek.



The Olentangy River rises in Morrow County, flowing to the west before turning south near Galion, and finally emptying into the dam at Delaware Lake. After exiting the dam, it continues south to join the Scioto River near downtown Columbus.

The stretch of the Olentangy River north of Columbus is popular for canoeing and kayaking and is central Ohio's only state-designated scenic river.