Dux

Dux is a noun that refers to the top pupil in school. 

Our word of the day comes directly from Latin where it can be used to describe a leader. Since the mid 18th century, dux has been used mainly in a scholastic context to describe the highest ranking student. Example:

I was the dux of our fifth-grade geography class. When it came to knowing the state capitals, I was truly the champ.