Captain G. Harry Stein was a Starfleet officer of the 24th century.

In 2364, he was the commander of the USS White Sands. Sometime in that year, he received an order about the Rigel/Andor subspace relays from Commodore Peter Bryce of the Starfleet Advanced Technologies Division. (TNG: "Conspiracy", okudagram)

This character was only mentioned in writing.
Stine was presumably named after the rocketry pioneer G. Harry Stine.