So I'm watching the 1954 version of "The Student Prince," and when I see Edmund Gwenn, all I can think of is Rygel. Gee, even the same moustache and haircut! Kind funny. Was there ever anything written as to what inspired Rygel's looks? Or the others? Or characters for other shows?
The most infamous thing like this is probably Contad Veidt's character in the 1928 film "The Man Who Laughs". The imagery is said to have inspired Batman's Joker; and the artistic similarities are a bit uncanny. http://filmmakeriq.com/2011/08/the-1928-film-that-inspired-the-joker-the-man-who-laughs
In the Batman comics they actually redesigned Alfred to look like the actor who played him in the Batman serials.
After giving it more thought, I've determined that Fish from Barney Miller is the true inspiration for Rygel.