At the moment, it’s uncertain what Star Wars films Darth Vader could feature in, but the next one will be announced later this week.
Lucasfilm intend to confirm the next spin-off and its director by the end of January.
But if it’s set during Darth Vader’s time in power, presumably he’ll be making an appearance.
Sadly, he didn’t feature in Solo, but considering the underworld focus, it would have been difficult to shoe-horn him in.
