Songchai Rattanasuban (Thai: ทรงชัย รัตนสุบรรณ; born: March 5, 1946 in Chachoengsao province) is a famous Thai Muay Thai and professional boxing promoter. He is well known for being a promoter of the fight titled "Suek Onesongchai" (ศึกวันทรงชัย; lit: "Songchai Day Battle") of Lumpinee Stadium especially in the 80's and 90's that have been recognized as the golden era of Muay Thai. He is the founder and CEO of Onesongchai Promotion, a Muay Thai and professional boxing promotion company based in Bangkok.