figurant

He played from a figurant to an international superstar, how great he is!

他从群演，最后成为一个世界巨星，了不！

Longtao generally means figurant, because they always wear Longtao robes to serve as a foil to main actors on the stage.

龙套”就是群演，由于他们都穿着各色的龙套衣而得名。