Mathlynn "Mattie" Langtor Sasser-Robert (born in 1996) is a Marshallese-born American weightlifter who currently represents the Marshall Islands. She competed at the 2016 Summer Olympics in the women's 58 kg event, in which she placed eleventh. She was the flag bearer for the Marshall Islands at the Parade of Nations. She will represent the Marshall Islands at the 2024 Summer Olympics in Paris.