Adewale Akinnuoye-Agbaje joined a gang of racist skinheads as a teenager.
The 'Suicide Squad' star grew up in Tilbury, Essex, during the 1970s, where he was a target for white nationalists and decided the best way to protect himself was to join them.
Adewale said: "I remember having to walk in my underpants. They made my life hell. I remember having dogs set on me...
"I still have scars on the back of my leg from the Alsatian."
I wanted belonging in a town where I was told I didn't belong. My father told me to stand up for myself. When I got proficient at that it got me a certain reputation."
The 52-year-old actor - whose new film, 'Farming', is based on his upbringing - was unofficially fostered out to a white couple and always felt "rejected" by his Nigerian birth parents, Baronet and Sikirat, who lived in London.
He said: "I felt my mum rejected me. But I was only six weeks old when I was passed on. As a child, those were my parents.
"When the rejection came was living in a house of eight to nine children, with rotating foster children."
And Adewale never felt loved by his racist foster parents.
He said: "I never recall getting a hug. We focused on survival. One of my earliest memories is my foster mother telling me she didn't like me."
The 'Thor: The Dark World' actor's biological parents took him back to Nigeria when he was eight years old, but he felt out of place there.
He recalled: "In school I was ridiculed as a foreigner. I couldn't speak the language and got beaten to make me speak."
He returned to his foster family when he was 13 and his life began spiralling out of control, culminating in a failed suicide attempt when he was 16.
He said: "It was the depths of my despair. I tried to put a noose round me and it didn't work."