Moon Seong-hyun is a South Korean actor born on June 2, 2006. He is known for playing the younger versions of male leads in several popular K-dramas, beginning his career in 2021.

He is managed by FNC Entertainment. He first appeared in the 2021 dramas Vincenzo and Hometown Cha-Cha-Cha. He gained significant recognition for his role as the young Seo Yul in the fantasy drama Alchemy of Souls and as Prince Simso in the historical series Under the Queen's Umbrella.