The Hollywood stars will help jury president Ruben Östlund award the Palme d'Or for best film.
Michael Douglas will be honoured with the award during the festival's opening ceremony on 16 May.
James Gunn was talked out of killing off the character by Marvel boss Kevin Feige and longtime MCU producer Louis D'Esposito.
The Gladiator 2 cast currently includes Paul Mescal, Barry Keoghan, Joseph Quinn, Connie Nielsen, and Denzel Washington.
Taika Waititi will reportedly direct the movie from a script by Dahvi Waller.
Allison Williams admitted working in the horror genre hasn't made watching the movies any easier.
Chris Evans turned to his friend and Knives Out co-star Ana de Armas about replacing Scarlett Johansson.
Joaquin Phoenix felt "lost and desperate" until he read the script for Paul Thomas Anderson's 2012 psychological drama, The Master.
Vince Vaughn is set to reprise his role as gym owner Peter La Fleur in the sequel.
Elizabeth Olsen is enjoying playing other characters in her break from Marvel.
Jessica Alba played Sue Storm in 2005's Fantastic Four and its 2007 sequel, Fantastic Four: Rise of the Silver Surfer.
Chris Pine joins Ariana DeBose and Alan Tudyk on the voice cast.
