Disney+'s Obi-Wan Kenobi means both its eponymous character and Darth Vader will equal an impressive Star Wars record. The Jedi Master reunites with his former Padawan and friend turned greatest enemy in the show, which gives Obi-Wan and Darth Vader a rematch set between the Star Wars prequels and the original trilogy and adds even more depth to their already storied history. The fates of Obi-Wan and Vader have been entwined since 1977, so it's understandable the Disney era would look to continue things in some way.
Few relationships in Star Wars are as fleshed out as Obi-Wan and Vader's, from the first tantalizing hint of backstory with the former's mention of fighting alongside Luke Skywalker's father (thought at that point George Lucas hadn't yet decided he would be Darth Vader) in the Clone Wars, to seeing it being realized in that TV show. Vader's return in Obi-Wan Kenobi simply marks the latest chapter, and it wouldn't be surprising if it's not the last either, but it's also the one that further hammers home their importance in Star Wars canon and sheer breadth of their involvement.
With Obi-Wan Kenobi, both the titular Jedi and Darth Vader equal a record for appearances in Star Wars canon, joining a brief list of characters who have appeared across all mediums: movies, animated TV, live-action TV, comics, books, and video games. Previously, this record was only held by four others: Boba Fett, Ahsoka Tano, R2-D2, and Luke Skywalker, all of whom earned it thanks to The Mandalorian season 2. Obi-Wan and Vader have, of course, appeared in multiple Star Wars movies, as well as throughout Star Wars: The Clone Wars (or at least, Anakin Skywalker did) and later appeared in Star Wars Rebels. Both characters have headlined their own individual comic book series and a joint one, appeared in various books - including Brotherhood, which centers around Obi-Wan and Anakin - and video games, including Star Wars: Battlefront II and Star Wars Jedi: Fallen Order.
Boba Fett and Ahsoka Tano's record made sense as fan-favorites of different generations - Boba the cool but underused character who was built up so much in the Expanded Universe, and Ahsoka the Padawan who helped define a new generation and become the face of Star Wars animation. But Obi-Wan and Vader - and in fairness, R2-D2 - have been instrumental across different movie trilogies, through animated and live-action TV, and headlined books and comics; the pair have shaped Star Wars canon and been involved in so many stories that they comfortably stand as two of the most important characters in the saga's entire history (as does Luke, though his role in animation is much lesser). They span prequels, originals, and even have their influence and legacy felt in the sequels; from George Lucas to Disney, Obi-Wan and Anakin/Vader remain integral to the fabric of Star Wars. Obi-Wan, of course, has the distinction of having his name attached to the TV show, but Vader is just as much of a headline draw.
With so many upcoming Star Wars TV shows, then there'll be further opportunities for others to join the list and add to the record after Obi-Wan Kenobi. Saw Gerrera, for instance, has been linked to Andor, and if that were to happen he'd be a part of it too having been in Rogue One: A Star Wars Story and Jedi: Fallen Order as well as various animated shows, books, and comics. But even with others matching it, few can claim the same kind of indelible legacy as Obi-Wan Kenobi and Darth Vader.