Agnes Tsao Kou Ying was a Catholic layperson from the Qing dynasty who lived in China during the mid-19th century. Born in Guizhou in 1821, she later moved to Guangxi to serve as a missionary, teaching the Christian faith to local families. Following government crackdowns on religious practice, she was arrested and imprisoned. Despite facing pressure from local officials to renounce her beliefs, she remained steadfast, eventually dying in captivity in 1856.