January Jones pulled a Joan Harris!
The actress, who's really made a name for herself playing blonde ice queen Betty Francis on "Mad Men," stepped out today with adorable son Xander ... and a fiery new 'do.
Gone are her famous golden locks -- as Jones was seen rocking a head of red instead!
No word yet on why she dyed her hair, as she's got nothing lined up on her IMDB page, but we want to know what you think of the look.
Vote in the gallery above -- and see more stars who have experimented with red hair!