短语 the leader of the pack 的意思是领头者，起领头作用。

例句

Bradley Wiggins is the leader of the pack in the Tour de France!

For many, Madonna is seen at the leader of the pack in the world of female pop stars.

请注意

短语 a pack mentality 的意思是跟着集体走，缺乏独立思考和计划，一种从众心态。

For example: The boys' pack mentality meant that they couldn't find their way out of the forest.