unapproachable
adjective uk/ˌʌn.əˈprəʊ.tʃə.bəl/ us/ˌʌn.əˈproʊ.tʃə.bəl/
（人）不友好的，难以接近的，令人敬而远之的
Someone who is unapproachable seems unfriendly or a little frightening, so that other people are less likely to speak to them.
As a boss I found him rather unapproachable. 作为老板，我发现他有点儿难以接近。