Lupita Nyong'o has said she was the "victim of colourism" as a child when she "wished to have skin that was different".
The Oscar-winning actor told BBC Newsnight that colourism "is the daughter of racism" in "a world that rewards lighter skin over darker skin".
Nyong'o was raised in Kenya, before moving to the United States.
She was speaking ahead of the release of her children's book, Sulwe, about a girl with darker skin than her family.
Colourism is prejudice against people who have a darker skin tone or the preferential treatment of those who are of the same race but lighter-skinned.
"I definitely grew up feeling uncomfortable with my skin colour because I felt like the world around me awarded lighter skin," the Black Panther star told Newsnight's Emily Maitlis.
She said her younger sister, whose skin was lighter, was called "beautiful" and "pretty".
"Self-consciously that translates into: 'I'm not worthy'."