Will Smith considered killing his father to "avenge" his mother.
The 53-year-old actor recalled how his dad William Carol Smith Sr. - who died of cancer in 2016 - was violent towards his mother, Caroline Bright, when he was growing up and admitted his father "terrorised" their family with his exacting standards, and he vowed to make him pay one day.
Will told how a shocking childhood incident between his parents "defined" who he is today.
In an extract from his memoir 'Will' published by People magazine, he wrote: "My father was violent, but he was also at every game, play, and recital. He was an alcoholic, but he was sober at every premiere of every one of my movies.
"He listened to every record. He visited every studio. The same intense perfectionism that terrorised his family put food on the table every night of my life...
"When I was nine years old, I watched my father punch my mother in the side of the head so hard that she collapsed. I saw her spit blood. That moment in that bedroom, probably more than any other moment in my life, has defined who I am."
The 'Men in Black' star admitted the trauma has had an impact on his entire life and career as he put on a front to hide his true self.
He said: "Within everything that I have done since then — the awards and accolades, the spotlights and attention, the characters and the laughs — there has been a subtle string of apologies to my mother for my inaction that day. For failing her in the moment. For failing to stand up to my father. For being a coward.
"What you have come to understand as "Will Smith," the alien-annihilating MC, the bigger-than-life movie star, is largely a construction – a carefully crafted and honed character – designed to protect myself. To hide myself from the world. To hide the coward."
Although Will retained a good relationship with his dad after his parents separated when he was a teenager, he admitted his anger from the childhood violence resurfaced years later while he was caring for his cancer-stricken parent and he contemplating killing his father.
He wrote: "One night, as I delicately wheeled him from his bedroom toward the bathroom, a darkness arose within me. The path between the two rooms goes past the top of the stairs. As a child I'd always told myself that I would one day avenge my mother. That when I was big enough, when I was strong enough, when I was no longer a coward, I would slay him.
"I paused at the top of the stairs. I could shove him down, and easily get away with it. As the decades of pain, anger, and resentment coursed then receded, I shook my head and proceeded to wheel Daddio to the bathroom."