The new Star Wars Jedi: Fallen Order game.
Fallen Order is widely regarded as one of the best Star Wars games in the modern era, and a sequel is already being developed. The story of the game takes place five years after the events of Revenge of the Sith, and the new Obi-Wan show is set to take place ten years after Revenge of the Sith. In the game, actor Cameron Monaghan voices and does the motion capture for Cal Kestis, a young Padawan who escapes the Order 66 purge of Jedi throughout the galaxy.
Since the timelines of Fallen Order and Obi-Wan overlap, this show would be a perfect opportunity to introduce a live-action Cal Kestis played by his original voice and motion-capture actor in Fallen Order. Of course, this could be little more than a cameo, similar to Ahsoka's first appearance in Cal's junk planet Bracca was featured heavily in The Bad Batch.
What's more, the imposing Fortress Inquisitorius makes a prominent appearance in the Obi-Wan trailer, having first appeared as the final level in the Fallen Order game. Cal has plenty of experience fighting the Inquisitors who will likely be the main villains of the Obi-Wan Kenobi series. These agents of the Dark Side are former Jedi, tasked by Darth Vader himself with hunting and killing any remaining Jedi who may have survived the initial Order 66 genocide. The appearance of the Fortress from the game could be another strong nod toward Cal's live-action debut. These connections are not being taken lightly by fans, and there are already several interesting Kenobi theories floating around online.
All this to say that it would be no surprise if Cal Kestis or any of his companions from Jedi: Fallen Order made an appearance in Obi-Wan. Ideally, Cal would be once again played by Cameron Monaghan, who is known for his incredible performances in shows like Gotham, Monaghan would make the perfect addition to the Obi-Wan Kenobi show on Disney+ as the fully realized Jedi, Cal Kestis.