What If...? cast is including:
Jeffrey Wright as Uatu / The Watcher (voice) (9 episodes), Terri Douglas as Additional Voices (voice) (8 episodes), Matthew Wood as Additional Voices (voice) (7 episodes), Robin Atkin Downes as Additional Voices (voice) (6 episodes), Fred Tatasciore as Additional Voices (voice) (3 episodes), Chadwick Boseman as Star Lord T'Challa (voice) (2 episodes), Michael Ralph as Additional Voices (voice) (4 episodes), Mick Wingert as Tony Stark / Iron Man (voice) (3 episodes), Piotr Michael as Additional Voices (voice) (4 episodes), Samuel L. Jackson as Nick Fury (voice) (4 episodes), Arthur Ortiz as Additional Voices (voice) (4 episodes), Josh Keaton as Steve Rogers / Captain America (voice) (2 episodes)