Variety revealed shortly after Episode IX began production that Doctor Who and The Crown actor Matt Smith was among the cast in what would be a “key” role. Since then there have been absolutely no details on what that role is. The leaks have not even really hinted that Smith was on the set at all.
During an interview with the LA Times Smith dropped a remarkably odd comment about his involvement in the movie he said “As far as I can tell I am definitely not (in Episode IX.)” I don’t know if this is intended to be a joke or if Smith’s role was somehow cut from the film. It could be possible that he was never on board at all. He was never included on the official cast announcement from Lucasfilm, but his quote is so short and vague that its pretty much impossible to tell what he means. Maybe the question marks about Smith’s involvement in the film will remain until we see it in December.
Some cast member have lied about their casting in Star Wars movies in the past. L3-37 actress Phoebe Waller-Bridge didn’t admit that she was in Solo until the first photo was shown that included her. Prior to that she insisted she wasn’t in the movie. Several outlets had reported that she was in the movie prior to that. Although, if you do flat out lie to the media it may be in your best interest for a Star Wars actor because then you can avoid Star Wars questions entirely.
I’m sure we’ll hear more about this one in the months that lead up to Episode IX.