I've had a few over the years:
1) an honors biology teacher in grade 9 who arranged for me to do original independent research on hominid biometrics at the American Museum of Natural History (New York City)--she fed my interest in science and research
2) an honors English teacher in grade 9 who had us dress up in togas to do Julius Ceasar & who signed me up for track--despite me not wanting to do it! He was my coach for several years later and would take me to other districts for coaching as my events (shot put, discus) were not his specialty. He had a joy in what he did that was engaging. He not only had me interested in literature from the way he brought it to life, but he extended my horizons re. sports. I ended up throwing shot put and discus--and later hammer and javelin--through my undergraduate college years.
3) 2 of college/university professors who challenged me to do my personal best and were there to support interests and ideas that extended beyond the classroom and spanned subjects both at the undergraduate and graduate levels.