Nguyen

The reason why there're only few surnames true to Vietnamese is because they're adopted after the kings of Vietnam, and there were only a few, thus you see a vast amount of common surnames, with Nguyen being one of the most common.

There is a slight difference between the surname Nguyen vs the first name Nguyen. Literally, it's the little "?" (which we all leave out when written it down for english, thus look the same).

u mean the ~ right? Nguyễn not Nguyển