Scarlett Johansson Offered Ghost in the Shell

[Christopher]

^Motoko's hair is purple.

 

[Set Harth]

It's purple in SAC. It's black in the films. It's blue in Arise.

 

[Christopher]

And it looks dark blue or purple-blue on the manga cover.

 

[Forbin]

I recently watched the 70s TV series live-action version of Lone Wolf and Cub. Quite wonderful.

 

[Reverend]

And it looks dark blue or purple-blue on the manga cover.

One of them, certainly. Others have it as black, dark brown, dark reddish-purple... Motoko's design has never really been consistent. Not just the hair, but her face and body type has changed wildly between and indeed within the various incarnations.
Indeed, the only constants are that she looks ambiguously young, attractive and Asian.