Ko Sung-hee (; born June 21, 1990) is a South Korean actress. She played her first leading role in the fantasy-period drama Diary of a Night Watchman (2014).
On October 17, 2022, Ko's agency announced that Ko will marry a non-celebrity boyfriend in November. They married in a private ceremony on November 20, 2022, in Seoul. On April 30, 2025, MSteam Entertainment announced that Ko gave birth to a daughter last year.