Are there any non-Japanese manga/anime authors or studios?
Don't know of a non-Japanese studio that produces only anime, but the series Oban Star Racers was produced by a French studio, "Sav! The World Productions" along-side Bandai and Disney.

The Studio 4C production "First Squad" has writing credits to Russian studio Molot Entertainment Film.

As far as mangaka, there's a lot of Korean manwha artists/writers that get published in Japanese serials. I don't think that necessarily makes them "mangaka". The series "Blade of the Phantom Master" by Youn In-wan was serialized in "Monthly Sunday Gene-X" in Japan (published by Shogakukan). Shin Yong-Gwan also had his first couple of works published in "Young Champ". 

As far as the western world Frederic Boilet is probably the most well known, born in France but draws comics in Japan.