This article is written from a real world point of view. Katelyn Mager (born April 22, 2001) is a Canadian actress from Vancouver. She portrayed young Thalia in the film adaptation of The Sea of Monsters. See also Katelyn Mager on IMDb Katelyn Mager as Young Thalia Grace. Retrieved from "https://riordan.fandom.com/wiki/Katelyn_Mager?oldid=550139" Categories: Real world articles Film cast People Actors Female Actors The Sea of Monsters actors Demigod Actors Young Demigod Actors Articles needing improvement Community content is available under CC-BY-SA unless otherwise noted.