(Full disclosure: I am a redhead.)
What it means: Apparently, going along with the stereotype that redheads have hot tempers, it also goes without saying that we are plotting everyone else's demise. Yay!
Redhead villains: Poison Ivy AND The Joker in the Batman series, Hilly Holbrook in The Help, Syndrome from The Incredibles, Victoria in Twilight, Big Red in Bring It On, Van Pelt in Jumanji, and of course, Chuckie in the Child's Play films. Look, it happens a lot.
Why it should be retired: In all fairness, plenty of heroines are redheads in film. But when it comes to depicting redhead males in film, it's just a little offensive, at this point. In other words: stop picking on us, or I'll kick your ass.