Marvel's Black Panther almost looked exactly like the Hollywood superstar Vin Diesel, and a longtime Black Panther writer confirms this longstanding rumor as fact. Black Panther has had many appearances in the world of Marvel Comics, but during a relaunch of the character that saw many elements changed, a key change was the look of the superhero entirely. Gone was T'Challa, son of King T'Chaka; the book's radical retool of the character didn't stick, however, and neither did the Vin Diesel-inspired look.
This is not the first time that the look of a character in Marvel Comics would be inspired by a real-world actor. In the Ultimate Marvel universe, the character Nick Fury was redesigned to strongly resemble actor Samuel L. Jackson. Reportedly, Jackson was not consulted on his likeness being utilized in comic book form. He eventually consented with the stipulation that he would play the character should a live-action film starring Fury ever come to fruition. Vin Diesel was similarly never consulted, but his likeness never ended up being used in the first place - though he came very close.
In the early 2000s, in the aftermath of 9/11, Marvel decided that Black Panther needed an overhaul. Rather than reboot the universe of the character, writer Christopher Priest elected to tell the story of a new character: Kevin "Kaspar" Cole. Cole was the farthest thing from a Wakandan king possible: he was a police officer in New York, struggling with rent, his relationship with his girlfriend Gwen, and other everyday problems of life in the city. According to Priest, "[Artist] Oscar Jimenez...dove into the project, coming up with our model for Kaspar Cole: Vin Diesel. Once we had the Vin idea and the right color palette and such, Oscar just ran with it."
Unfortunately, plans for Vin Diesel fell through. Jimenez left the project and was replaced by Dan Fraga, who also left the Black Panther retool. While Kaspar Cole eventually made it to print, he no longer had the appearance of Vin Diesel, thanks to some communication difficulties between Christopher Priest and new artist Jorge Lucas. "There were some language and cultural barriers between Jorge and I, and some of our pop culture concepts (Kasper as Vin Diesel, for instance), got lost somewhere along the way." Eventually, the White Tiger soft reboot couldn't overshadow T'Challa's legacy, and the character was brought back (although in a way, he never actually left; such is the benefit of a soft reboot rather than a universe-rewriting Crisis-esque story).
Unfortunately, T'Challa will have to be replaced in the MCU, thanks to Chadwick Boseman's tragic passing in 2020. Neither Marvel nor Disney ever entertained any notions about recasting Boseman, so a new character will have to don his mask. While it's currently unknown of Kasper Cole will be in Black Panther: Wakanda Forever, it's almost a certainty that Vin Diesel won't play the character.