John the Orphanotrophos (Greek: "caretaker of orphans"), is the chief court eunuch (parakoimomenos) during the reign of the Byzantine Emperor Romanos III (r. 1028–1034).

John was born in the region of Paphlagonia and his family is said to have been engaged in some disreputable trade, perhaps money-changing or, according to George Kedrenos, forgery.

John is the eldest of five brothers.

Two, Constantine and George,are also eunuchs, while the other two, Niketas and Michael, are 'bearded' men; the latter becomes Michael IV the Paphlagonian after John introduces him to the reigning empress Zoë.

According to Michael Psellos, the two became lovers and hatched a plot to assassinate Zoë's husband, then reigning.

Romanos is killed in his bath on April 11, 1034.

Certain contemporary sources implicate John in this assassination.