Antonio C. Santillan (born April 15, 1997) is an American professional baseball pitcher in the Cincinnati Reds organization.
Santillan was added to the Reds 40–man roster after the 2019 season. He did not play a minor league game in 2020 due to the cancellation of the minor league season caused by the COVID-19 pandemic. On June 12, 2021, Santillan was promoted to the major leagues for the first time. Santillan made his MLB debut the next day as the starting pitcher against the Colorado Rockies, pitching 4+2⁄3 innings of 1-run ball with 5 strikeouts. He recorded his first career strikeout versus Rockies shortstop Trevor Story.