The Mad Men star, famed for her flame-red locks, has revealed she is a natural blonde, but started dying her hair as a child with the help of her mother.
Hendricks admits she modelled her look on the red-headed heroine of Lucy Maud Montgomery's 1908 book.
She says, "I'm naturally a dark blonde. I couldn't tell you what shade because I haven't seen it in ages. I started playing with red hair when I was 10 years old. I recognise how odd it is now, but my mum let me do it.
"I was obsessed with Anne Of Green Gables. There was something about her that spoke to me - and I wanted to have her beautiful red hair. My mum said, 'Well, let's throw a rinse on it.'
"My hair was very blonde at the time, but it went carrot red. And I was over the moon. I went to school the next day and felt like myself."
The actress went on to try out a number of different shades before she eventually went back to red, adding, "In high school, I started experimenting with permanent colour. My mum nearly cried one day when I came down the stairs in jet-black hair.
"I got purple, pink and black out of my system during those years. I was a goth kid. I dyed my hair about 42 different colours, shaved it at the back and wore black make-up."