She is probably know best for her golden Grace Kelly-style locks but January Jones has also been a brunette and a redhead in the last few years - but is now paying the price for her changing hair colour.
The Mad Men star has revealed that she is losing her hair because constantly switching hair colours is taking its toll on her scalp.
Speaking to Grazia Daily at the Sundance Film Festival, the 35-year-old said: "I have been every colour and now my hair is falling out in clumps."
"I like it all colours, it makes you feel different according to what colour it is, but I prefer to be blonde. My son recognizes me in photos when I am blonde. He says, 'Mama'.
"I've been blonde, red with extensions for this film, then blonde, then black, and now blonde again. I'm going to have to shave it off and wear a wig"
She is not alone - Lady Gaga and Kelly Osbourne have both reportedly suffered hair loss due to stresses and strains on their scalp, with Kelly admitting to the the Guardian that she had bald patches and said: "I felt like I'd been electrocuted and burst into tears."
January was at Sundance to promote her new film 'Sweetwater', in which she plays a former prostitute in 1800s New Mexico, who seeks revenge against the men who killed her husband.
She will return as Betty Francis in the sixth series of Mad Men, due to premiere in April in the US.