Go Yoon-hwan (; born August 26, 1998), better known by his stage name Ryeoun (), is a South Korean actor. He is best known for his roles in 18 Again (2020), The World of My 17 (2020), Adult Trainee (2021), Twinkling Watermelon (2023), and Weak Hero Class 2 (2025). In 2023, he had his first and second television lead roles in The Secret Romantic Guesthouse and Twinkling Watermelon.
In 2026, Go starred in Disney+'s crime thriller television series Bloody Flower opposite Sung Dong-il and Keum Sae-rok. It is based on the novel of the same name by Lee Dong-geon.