Robert Downey Jr. took part in ABC's Chadwick Boseman - A Tribute for a King that aired on ABC last night. The Iron Man actor called Black Panther the "crowning achievement" of the Marvel Cinematic Universe. Last night's tribute to Chadwick Boseman took in over 10 million viewers, easily winning the night as MCU fans gathered to remember the T'Challa actor along with a commercial-free screening of Black Panther. Robert Downey Jr. had this to say about Boseman during the tribute.

"Toward the end of the third Avengers, Infinity War, we all kind of lose together. And I remember it was one of those few days when all of the Avengers were together, and it was just the way he walked on set, and the immense success that had occurred, and rightfully so, with Black Panther. And he was just in this kind of stratus of his own, but always, always humble, always hardworking, always a smile on his face. And now, looking back, all the more, I realize just what an incredibly graceful human being he was."

Black Panther director Ryan Coogler also echoed Robert Downey's Jr.'s sentiment in his loving tribute released over the weekend. Coogler, and Downey Jr. had no idea that Chadwick Boseman was sick, it seems that only those closest to him in his family were aware of the cancer diagnosis, which means he was sick while making Black Panther, which Robert Downey Jr. has some strong praise for.

"And Black Panther is, hands down, it is the crowning achievement of the Marvel Universe, and I say that with all due respect to all the films that have been made, including my own. But it was the one where people got to vote with their ticket sales and say, 'We require this overdue diversity, this is a meritocracy, or at least it should be, and this is a fantastic movie that has leveled the playing field', and appropriately so. His legacy is so meaningful."

Obviously, Chadwick Boseman will be remembered for more than just Black Panther. But, that was the movie that turned him into a superstar. Before playing T'Challa, he portrayed legendary singer and performer James Brown in Get On Up. The movie's director, Tate Taylor, was taken aback by Boseman's dedication to his craft and his way of collaborating. Taylor had this to say.

"Chadwick was a perfectionist and a consummate professional. He shared my love of collaboration. He believed, like me, that good ideas can come from anybody anytime, anywhere. But he also taught me about dedication, resilience and so much about love. He listened to me as a partner, not as a critic. If he or I questioned the other's opinion, we talked about it openly and deeply and always ended up with a solution neither of us saw coming. He let himself go in his performance without any sense that people were watching him."

"It was unlike anything I'd ever seen. He stayed in character not because that was his method, but because he became James Brown. He would strut up to my first AD (a beautiful blonde from Mississippi) pull her into his arms and as Mr. Brown says, 'Hey pretty white lady, Mr. Brown needs a sandwich' then give her a gentle kiss on the cheek. At one point my AD looked at him and begged Mr. Brown to never leave her."

Tate Taylor went on to say, "Chadwick Boseman wasn't just a talented actor, dancer, writer or superhero, he was a beautiful, majestic creature put on this earth to help people." This is another sentiment that has been brought up by several of Chadwick Boseman's colleagues. Taylor continued, "He changed everyone he ever met or worked with. I am one of those fortunate people. I'll be talking to Chadwick just like Mr. Brown did with him because as James Brown always said, 'You can't stop the funk.'"

Chadwick Boseman also tackled the role of Jackie Robinson in 2013's 42 and received praise for his work alongside Harrison Ford. Black Panther was the role that kicked down the doors and made Boseman a household name, even for people who don't normally watch superhero movies. Thankfully, he left behind a legacy that people will be able to enjoy, and discover, for the years to come. You can watch Robert Downey Jr. pay tribute to Boseman above, thanks to the Good Morning America Twitter account.