Masaki Aiba (相葉 雅紀, Aiba Masaki) (born December 24, 1982) is a Japanese singer, actor, television personality, radio host and dancer. He is a member of the boy band Arashi.
Aiba began his career in the entertainment industry when he joined the Japanese talent agency Johnny & Associates in 1996 at the age of 13. Prior to his debut as a singer with Arashi in 1999, Aiba started an acting career when he was cast as the lead role of Gordie for the stage play Stand by Me, which was based on the film of the same name. About five years after his debut as a singer with Arashi in 1999, he became one of the co-hosts of the variety show Tensai Shimura Dōbutsuen (天才！志村どうぶつ園, Genius! Shimura Zoo) in 2004, making him the first member of Arashi to regularly participate in a variety show not primarily hosted by Arashi.