Sifo-Dyas is a human Jedi Master from Minashee, and for twelve years he was nothing but a line of dialogue: the Kaminoans tell Obi-Wan Kenobi that a Jedi called Sifo-Dyas ordered the clone army, and that he has been dead for a decade. The character had no face, no scene, and — for a long stretch of fandom — a persistent rumour that the name was a misspelling of Sido-Dyas or a stand-in for Darth Sidious.
The sixth season of The Clone Wars finally answered it in the arc that opens with "The Lost One": Sifo-Dyas was a real Jedi with genuine and disturbing visions of a coming war, he commissioned the army in secret because the Council would not act, and Count Dooku had him murdered so the Sith could inherit the order. He is the clearest case in Star Wars of a throwaway line being paid off, in a different medium, more than a decade later.
Catalogue entry. This figure has a verified record here rather than a full write-up — the encyclopedia labels its own depth instead of padding it.
