Black Panther director Ryan Coogler has spoke out about his relationship to the film's star, Chadwick Boseman, who passed away on Friday from colon cancer at the age of 43.

Paying an emotional tribute to the talented and notoriously generous actor, Coogler said that he hasn't "grieved a loss this acute before".

"Chad was an anomaly. He was calm. Assured. Constantly studying. But also kind, comforting."

The filmmaker said he "wasn't privy" to the details of the actor's private illness, reflecting on how he worked with Boseman but had no idea he had cancer.

"After his family released their statement, I realised that he was living with his illness the entire time I knew him," Coogler said.

"Because he was a caretaker, a leader, and a man of faith, dignity and pride, he shielded his collaborators from his suffering. He lived a beautiful life. And he made great art.

"Day after day, year after year. That was who he was. He was an epic firework display. I will tell stories about being there for some of the brilliant sparks till the end of my days. What an incredible mark he's left for us."

Coogler has been working on Black Panther 2, which was slated for release in May 2022. The details surrounding how Disney will handle the loss of the star are unclear.

"I haven't grieved a loss this acute before," Coogler said. "I spent the last year preparing, imagining and writing words for him to say, that we weren't destined to see.

"It leaves me broken knowing that I won't be able to watch another close-up of him in the monitor again or walk up to him and ask for another take.

"It hurts more to know that we can't have another conversation, or Facetime, or text message exchange. He would send vegetarian recipes and eating regimens for my family and me to follow during the pandemic. He would check in on me and my loved ones, even as he dealt with the scourge of cancer."

Coogler finished the message by describing Boseman as an "ancestor," adding: "And I know that he will watch over us, until we meet again."