My second-grade teacher. I went to a catholic school for kindergarten through third grade. I was a really smart little kid (once they tested me in third grade they wanted to bump me up to fifth), and as such I got my assignments done early in kindergarten and didn't have anything else to do so would get bored. The teacher labeled me as a 'bad' kid because of this (yes, I was a bad kid because I was too smart, even though I was a really quiet, shy, and reserved), and it was one of those schools where your label will stick with you as you go up grades, regardless of how you actually are. First grade was pretty miserable, but I managed to get by. A bully broke my ballerina figurine for show and tell and neither the teacher nor the principal cared. But it got even better the next year.
Second grade was a nightmare- extreme punishments for perceived slights, and general bad treatment because I got done with things fast and knew most things we were doing already. The capstone of why that grade was the worst was when we were to go on the class field trip. I was told that I couldn't go. When I brought my parents into it, they were told that it was because I hadn't done some assignment, and the teacher was going to give me a collection of assignments (that nobody else had to do) to stay and do in class while everyone else went to the park. Needless to say my parents were furious, and kept me out of school that day. They didn't want me to go to that school anymore, but our options were very limited. Fortunately, a new teacher came into the system for third grade and provided me with opportunities and treated me like I was an actual person. My parents pulled me to be homeschooled for fourth grade while they looked for a better school system, especially after the fourth grade teacher's continuous talking about how she 'couldn't wait to get her hands on me'.
Wonderfully enough, within a few years after I stopped going there it was shut down.