In an interview with Irish Central, Neeson, who was once an aspiring boxer, spoke about his love and admiration for "The Greatest," calling him "a giant of humanity."
"He was my hero from when I was a young amateur boxer, and schoolboy, back in Ireland. I'll never forget hearing that he had beaten the unbeatable Sonny Liston. It was 1964 and it was a cold, wet February in Ballymena," Neeson said. "As I walked to school that morning, my feet didn't seem to touch the ground: my mind was an excited blur, because somehow the world had changed with that victory."
The actor also shared stories about meeting Ali.
"I got to meet him before he had his last fight in 1981. Not knowing what to say and with my knees shaking, I said 'Muhammad, I love you.' He gave me a hug and then signed an autograph for my father," Neeson said.
He continued, "I met him again in 2011. He was unable to speak with his advanced Parkinson's. I put my hand over his and whispered 'I love you.' His wife said to me, 'He knows who you are.'"
Neeson then said that there's not one movie star whose charisma could ever compare to Ali's.
"He was a giant of humanity," he said. "As a people, we are all in bereavement."
After news of Ali's death, other stars, including Madonna, Chris Rock and Jennifer Hudson, took to social media to express their sadness and share touching tributes.
Ali, who had Parkinson's disease, died at a hospital in Arizona, where he had been treated for respiratory issues. The cause of death was septic shock from unspecified natural causes, Reuters reported Saturday.