Ryujin
Legend
If "Obi Wan" has shown us anything, it's that Jedi age like a fine wine; Spend decades in relative ease, improving with age, and then are exposed to heat and quickly turn to vinegar.It was 10,000 at the hight (i.e. Episode 1). They were already depleted by the Clone War before Order 66. But he would have been about 50 - not an age to be an obscure padawan, he would have been either senior or a washout. Even if he hadn't been on screen the Inquisitors would have pictures of senior jedi. He would be recognised on Coruscant.
And Failed Jedi doesn't seem to fit the narrative. If he was already failing before the Empire, he didn't have that much to sacrifice.