局内人 用英语说

insider = 内部的人,圈子内的人; 例子:
内部人对公司股票的操纵 = manipulation of a company's securities by insiders.

those (people) in the know = 知道内情的人,局内人; 例子:
知道内情的人都三缄其口. = Those in the know are not talking.

participant = 当局者; 例子:
The participants in a chess tournament are often not decisive about their next moves. 棋赛选手常常有当局者迷的困惑.

英语裏头有不同的表现,可以用来翻译"局内人", 您如果用中文擧几个具体例子,我可以试给你翻出来看看.

局外人是 outsider!It's not outlier.
so ,局内人may be insider..

inlier呗

the insiders