Thresh's sister is a citizen of District 11. She is presumed to be raised by her grandmother along with her brother, Thresh. She was only mentioned on the 74th Victory Tour. Katniss was certain that she was shot, after hearing gunshots that she knew killed an old man, but was proven wrong by Seeder, as when Katniss asked Seeder before the start of the 75th Hunger Games, she answered: "they are alive." Her current fate is unknown.
In the book, Katniss describes Thresh's sister as tall and muscular, just like her brother.
Thresh's sister does not appear in the film.