The young actor started with minor roles and eventually emerged as a movie superstar.

emerged 是动词 emerge 的过去式。emerge 由前缀 e-（表示"向外"）和 merge（"合并、融入"）组成，字面意思是"从...中浮现出来"，引申为"脱颖而出、崭露头角"的意思。在这里指演员从默默无闻的状态中脱颖而出成为明星。