I'd have to say that after watching nearly all the Chan films over the years, my favorite non-Chan character would be Doctor Zodiac in 'Charlie Chan at Treasure Island'...

What an interesting & pleasurable subject for consideration! I am roused from the trance that always envelops me when i find myself in years beginning with "2" to want to put down my cellphone & put my gray cells to work on this question. It won't be an easy answer for Chan fan, i should think, with so very many impressing characters to consider. I applaud LIN for introducing the topic, and endorse Dr. Zodiac as possessing the background and temperament the nation requires in a nominee to this important post. I'm sure that if the Senate confirms him he will revolutionize the other end of the judicial telescope and make crime and criminals more entertaining!
.....Should Dr. Zodiac be unable to carry out his duties, or disqualified by the judges, a second runner-up will be called upon. As a recent but frequent visitor to the House on Punchbowl Hill (smooth move, Charlie, buying before the riffraff moved in!), i imagine i may be called upon to cast my weight to the wind and so am taking Lin's proposition into my dimly shadowed study for consideration. The appearance of smoke from my chimney will announce that i've selected my candidate, or that my significant other has taken threatened action & begun burning the books said to contribute to the dim shadows.
.....As i retire to consider this and other questions that beset modern (wo)men and non-binaries, i'm reminded of an interesting if not precisely relevant prior case. In conjunction with the release of The Simpsons Movie, one of its sponsors Burger King offered a website that allowed visitors to "Simpsonize Yourself!" I have to admit i did not try it, only as to my sorrow i didn't learn of it until after the limited time offer expired. (Rarely have i regretted cutting back my consumption of fast food, but this miss was one i'd pay to remedy. Alas.)
.....Not that i'm suggesting it, but the pop-up of the Simpsonize Me program (how DID they do it?) kicks a number of possibilities into my mind: were there a way, could a new character (like, say, me?) be inserted (by the same magic wondered about in the previous sentence) into any of the works that comprise the Stations of the Chans? Could any of the several Charlies be lifted whole (same magic) from the Canon, & put down into the draggy, inferior wearily-plotted, "celebrity"-based "detective" pieces that roll out of today's Hollywood?
.....It's said that when an appliance maker digitally dubbed their product into a Fred Astaire dance routine, it "didn't test well". Consultants blamed it on Fred's decease---i consider THAT a discrimination against a very silent MAJORITY---i myself blame it on a public that not only wouldn't recognize Fred if he'd just been presented to him; wouldn't know "how" to watch a real movie if they'd try; who are so smug in their assurance that generation means everything & that only theirs matters, and who regard Fred Flintstone as another dead white male. I submit, yet, that the effort with Fred Astaire---a sublime bit of concept from someone in a "creative department"---was yet only a candle beside the sun. As the original lyrics to "Helter Skelter" went, "he may be a dancer but he ain't the celebrated detective Charlie Chan". Today's media, and cinema, languish. Charlie Chan is waiting in the wings, or in the Wong's Dim Sum nearby.
.....We have the true Grail, we Chan fans. (Or is it "us Chan fans"? Lemme see, "Us have the..." Nope, it's we.) And it is WE. Why anybody is anywhere else on Monday nights is a mystery i'm not interested in solving. I've gained so much from our gatherings, had such a good time, found that the best things in life come from other people. Such as Lin, with this new view of the venerated treasure left by Earl Derr Biggers, enhanced by armies of actors, and polished with enthusiasm by those who love him. An idea to consider, and a place to be. What else is there?
.....Just THANKS!

This is a tough question. There are many characters in the Chan films that are memorable. For me, probably Tarneverro, played by Bela Lugosi in "Black Camel" is my favorite non-Chan character.

On a related note, my least favorite character in a Chan film is easy - the character Marcel, played by Harold Huber in "City in Darkness". He is too loud and bumbling, and ruins the movie for me.

Dear Lin,

That's a great question! I will have to say that my favorite non-Chan character would probably be Gravelle, played by Boris Karloff in "Charlie Chan at the Opera." Another one that has grown on me over the years is Sheriff Mack in "The Jade Mask" probably because of his dry humor and the way he goes along with Charlie Chan without trying to assert his local authority as other officials have in other Chan adventures.

Thank you, again...so much...for the fun question, Lin!

Sincerely,
Rush Glick