Phylicia Rashad Remembers Former Student Chadwick Boseman (Exclusive)

The TV legend chats with ET about her latest film, 'Black Box,' now streaming on Amazon Prime.

Phylicia Rashad was one of the first people who saw Chadwick Boseman's raw talent back when she was his acting professor at Howard University. The Cosby Show matriarch and star opens up to ET's Kevin Frazier about her relationship with the late actor, who died from colon cancer on Aug. 28, at the age of 43.

"I remember his smile and his gentle way. I remember his unending curiosity and his love of study, studying many things all of the time," the actress recalls. "When I look back on his body of film work, and I have been able to see quite a bit of it in these last few weeks, it never ceases to amaze me how very different he is in each and every role. And the differences are subtle. They are not sweet rolled, they are not manipulated, they are not contrived. He presents a real person and persona in every character he plays."

Rashad did more than teach Boseman, she also called upon her famous friends, like Denzel Washington, to help finance his acting school abroad. After graduating, Boseman went on to star in many memorable and inspiring films like 42, Get on Up and Black Panther.

"I am going to say this for the first time, but it amazed me that his portrayal of James Brown did not garner an Oscar Award, not just a nomination but award," Rashad reflects. "When you talk about someone going deep inside themselves to step out of themselves, and to present a human being that we know superficially and to go deeper into the psychology of that person, that was phenomenal work."

Aside from teaching him the craft of acting, Rashad knew a side of Boseman that many others didn't.

"When he came to New York, after graduating from Howard University, one day he called me all excited, 'Oh Ms. Rashad, you will never guess what I am doing,'" the actress remembers, thinking he landed a big Broadway gig. "You know what he was doing? He was working with young people at the library and he was excited about it. That's who Chadwick was."

Rashad, meanwhile, returns to the screen in the Amazon Prime psychological thriller Black Box. In the film, she plays Lillian, a neuropsychiatrist who helps restore the memory of a younger father, played by Mamoudou Athie, who lost his wife in a car accident.

What Rashad loves about her character is "her intention." "Her underlying attention," she notes. "And the fact that she's a really, very well developed official woman and she is tops in her field."

As for working with Athie, who's making a name for himself in the industry. This year, he was nominated for an Emmy Award in the Outstanding Actor in a Short Form Comedy or Drama Series category for Oh Jerome, No.

"Mamoudou, he really goes down and takes the elevator ride down of the subconscious of the character and he is a treasure. Yes, he is," she said of her co-star.

Black Box is now streaming on Amazon Prime Video.