Tobi, a male human who belonged to the Jedi Order, served as a Padawan under the tutelage of Mitaka. Despite the fact that Tobi died in the Great Jedi Purge that occurred after Order 66, Mitaka managed to transfer Tobi's soul into a droid referred to as T0-B1. Equipped with a Kyber crystal as its power source, T0-B1 possessed Force-sensitive abilities and harbored ambitions of becoming a Jedi.
The character of Tobi was conceived to provide context for the Star Wars: Visions short film "T0-B1," but he wasn't actually referenced in the episode itself. His character's details were subsequently defined in The Art of Star Wars: Visions.