There's a lot that goes into Darth Vader's menacing on-screen presence, but a huge reason why the Sith Lord is so terrifying is his voice.
James Earl Jones' vocal talents were behind Darth Vader's most iconic lines, such as when he said, "I find your lack of faith... disturbing." So, when Hayden Christensen was confirmed for Obi-Wan Kenobi as Darth Vader, some fans were disappointed. While Disney could always work its magic to try and make Hayden's voice deeper to match Jones', there's no beating the real thing.
Having said that, the latest Obi-Wan Kenobi episode revealed that Jones is back as Darth Vader.
Prior to the premiere of Obi-Wan Kenobi Part 3, Jones was uncredited and unconfirmed for the latest Star Wars spin-off. However, following the appearance of Darth Vader (SPOILER ALERT), the end credits finally listed Jones.

