I believe that I can learn something from everyone but not everyone has something to teach me.
As far as MA go, I have had 5 people who I consider to have been my teachers. My first was Melinda Bear. She taught me TKD but she also taught me (by example) what a good MA instructor should be and I used that knowledge to find my other teachers and they've all been good.
My second was Shihan Larry Davenport. I trained in Okinawan Goju-Ryu with him. More than anything else, though, he taught me the importance of the basics. I still visit him when I am near his dojo and still work out with him on occasion.
My final three instructors are people I still actively train with on a regular (if not always frequent) basis.
Guru Ken Pannell is my Sikal instructor. He is my primary instructor. He is a mentor to me in a wide variety of ways in and out of the MA. My dad is still alive and we're very close so I don't consider Guru Ken to be a father figure for me but he's definitely like a favorite uncle in many ways. And in other ways he's a close brother. Mostly, though, he's one of my best friends.
Bapak Willem "Uncle Bill" de Thouars is my Kuntao Silat de Thouars instructor. Uncle is an amazing guy. He's very friendly with a lot of good knowledge to share and I feel very proud to call him one of my teachers. But beyond what he's taught me about MA, he's shown me the importance of keeping a young and fresh mindset in life in general. There's a great quote by Teresa Langdon that I love: "Believe as a child believes and the magic will find you." Uncle embodies this quote and he is most definitely magical.
Professor Joe Lansdale is my Shen Chuan instructor. Prof. Lansdale is like a magician, too. He does things with his MA that seem, at first, like magic. Then he starts explaining them and the next thing you know, you're doing them. Outside of MA, though, he's taught me (directly and by example) a lot about writing and communicating in general.
A couple of honorable mentions would be Guro Dan Inosanto and GM Cacoy Canete. I don't consider either of these men to be direct instructors to me because I haven't spent enough regular time with either of them. However, they have both had huge impacts on me both as a martial artist and in general. Guro Dan is my role model for humility. He is an incredibly skilled MAist with a lot of knowledge and background but he never hesitates to set what he knows aside and put on a white belt (literally or metaphorically) and learn what others have to teach him.
GM Cacoy is my role model for enjoying life to its fullest. In his mid-80s he's still full of energy and life. He's able to not only beat people in sparring who are 1/4 his age but he's able to play with them, instruct them, and have fun while he does it. He cackles the whole time he's beating the tar out of someone - and, while painful, the beatings are actually very light (compared to what he could be doing) and instructive.
Mike