Who was the sniper GI Joe in Robot chicken?

You are likely thinking of "The Sniper" from the Robot Chicken episode "The Ballad of the GI Joes," not "GI Joe" himself.

He is a silent and incredibly deadly sniper, a member of the GI Joe team who is shown to have a complex and somewhat dark personality.

The character is voiced by Seth Green, who is also one of the creators of Robot Chicken.

Fun fact: The Sniper's character is actually a parody of the classic "Silent Scope" video game series, where players control a silent sniper.