This is a tough one. When this question came out it made me really have to stop and think. I was EXTREMELY shy as a child but I loved school.
My first grade teacher - Mrs. Howell - I was terrified of her. At that time corproal punishment was allowed in school and she was the one that gave it out (in my child's mind's eye she was a BIG woman). She paddled kids in the bathroom located in our classroom. Needless to say I would not go to the bathroom all day.
Mrs. Carpenter was 2nd grade. Other than my remembering she was very pretty I don't remember much else. So not much of an impression there.
Mrs. Gribble was my 3rd grade teacher. Again, award times. I don't remember much more than getting in trouble with her for reading a cussword written on the wall by the pencil sharpener. I had no idea what the word was or what it mean, but by saying the "F" word I earned a timeout in the hall and a trip to the principals office. Luckily Mom was the PTA president and best friends with the principal so that ended well.
Mrs. Hoover was 4th grade. I did like her. I remember her praising me because she wrote the word "chrysanthemum" - heck not sure I even spelled that correctly - and I was the only one in the class who could pronounce it. :-)
Mrs. Askew was my 5th grade teacher. She and I are still in touch so I guess she wins out. She was a very positive person and worked hard to get me out of my shell.
I don't even remember any of my middle school teachers. High school had a variety of teachers - each contributing some to my coming out of my shell. I remember Coach Flannigan telling me I was a parent's wet dream because I made good grades and was into sports. But I had to prove myself to him. He was the girls basketball coach. I swam competitively year round. He though all swimmers were wimps. That was until I outbenched his star basketball player and outperformed his entire team in all of our athletic contests. He changed his mnind about me then and went out of his way to support me.
I do remember Mrs. Westaway, my English teacher senior year of high school. She was very influential in my life - but also English was the class I had with all my best buds - so it was a fun class.
In college - I would have to say Tibor Machan - one of my Philosophy profs had the biggest influence. He was this HUGE Hungarian dude. Loud and at times really intimidating. For some reason he took a liking to me and encouraged me all throughout my time at Auburn.
But to be honest, the one teacher who made the biggest impression on me? My Mom. Truly. She taught 6th grade to inner city kids in Atlanta in the turbulent 1960's. She saw it all. Mom instilled in me my love of learning and challenged me to stretch myself. She was my biggest fan and my biggest coach. She encouraged me all through school all they way to my graduation from Ga. Tech with my Masters.
so my most influential teacher - my Mother - the one who was with me at EVERY grade, through every class and through EVERY life lesson. She truly was the wind beneath my wings and the reason I am the woman I am today!