A eunuch — either a castrated male or a court official (the terms overlapped in antiquity). The Ethiopian eunuch of Acts 8 is the New Testament's most famous example: a powerful court official who, despite being excluded from the temple assembly (Deuteronomy 23:1), found full inclusion in Christ through Philip's preaching.
The eunouchos of Acts 8 is a gospel revolution in one story. Under the old covenant, eunuchs were excluded from the assembly (Deuteronomy 23:1). Isaiah prophesied their inclusion (Isaiah 56:3-5). In Acts 8, it happens: the Ethiopian eunuch — Gentile, sexually other, geographically remote — is baptized and goes on his way rejoicing. Every barrier falls before the gospel. The eunuch's story declares that in Christ, no one is excluded.