Scarlett Johansson is following in the footsteps of Beyonce Knowles, Milla Jovovich and Andie MacDowell, by signing up to promote haircare giant L'Oreal.

The Lost In Translation beauty, 21, modelled in Calvin Klein and Louis Vuitton campaigns last year (04), and now she's reportedly planning to embark on her biggest endorsement deal to date.

A source says, "It's going to be a massive multimedia campaign, and Scarlett is making over $4 million for her services.

"One thing you'll probably see is Scarlett trying out a lot of different hair colours and not just her trademark platinum blonde look."