Avoxes. Suzanne Collins says they are mute and redheaded. According to stereotypes, this may seem like an oxymoron.
However, once you get past this point and realize some redheads are portrayed as shy or mute (see Charlie Brown's Little Redheaded Girl in the Corner, who is never shown or heard), note that the Avoxes are made to be slaves by the Capitol.
And the Capitol fashions are crazy. Effie Trinket has bubble gum pink hair because it's stylish. Others have green, blue, purple hair. Tigris, in book 3, has work done to make her look like an actual tiger.
But no one is voluntarily redheaded.
Only the Avoxes are mentioned as having red hair, and in book 3, Katniss even mentions that the people living in the Capitol refer to them as "the redheads".
The least-respected human beings, those being punished as traitors or otherwise, who have their tongues cut out, are redheads. Gee Suzanne Collins, tell us what you really think? Being red haired is a punishment in her eyes. Or she's making a commentary on the public status of gingers. Or was this a way to make a point about racism without seeming racist a la MIA. Or no thought went into it at all. Or she copied it from "Battle Royale" or "The Giver" or another one of the young adult books she stole ideas from...
Maybe, for Halloween his year, I'll be an Avox! As long as redism gives me Halloween costume ideas, I won't try to start a redist revolution against "The Hunger Games".
Oooh...maybe we can create an Avox-themed flash mob!?
Edit: Oy vey, I forgot about Foxface.