Z. Olgyay was a Human Starfleet officer in the 22nd century.
In January of 2155, he was listed as an Orbital Mechanics officer on directory placards at Starfleet Command's Fleet Operations Center, Sol Sector. His office was located in room #3453. (ENT: "Demons", directories)
This character was only mentioned in writing.
He was named after Enterprise propmaker Zoltan Olgyay.