For those such as myself who were unfamiliar, Thrawn is a character from the expanded Star Wars universe - he first appeared in the 1991 novel 'Heir To The Empire' and has since featured in numerous animated series, video games and his own collection of stories. However, I stated that the list would only cover characters from the first eight episodes ('Phantom Menace' to 'The Last Jedi)' and the stand-alone 'Rogue One' film as these are the only ones considered canon. The fact that I had to Google who Thrawn was illustrates that he has yet to appear in the wider, non-fanboy community. Frankly, I haven't the time to explore the endless expanded universe of Star Wars for a definitive list so I hope you'll forgive me for that.