D. Gabrielle was a Starfleet officer in the 23rd century.

In 2285, this individual was a commander at Starfleet Academy's Starfleet Training Command. They were an Inter-stellar Ethnology instructor. Their office, located on the second level of a building, was in room #208. Rank, name, position, and office were listed on a directory placard. (Star Trek II: The Wrath of Khan, set artwork)

This character was only mentioned in writing.
The placard was sold on It's A Wrap! sale and auction for US$31.99. [1]