J. Longo was a Starfleet officer in the 23rd century

In 2285, he was a lieutenant commander at Starfleet Academy's Starfleet Training Command. He was an Engineering instructor. His office, located on the second level of a building, was in room #210. His 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.
He was named after property master Joe Longo. The placard mentioning this lieutenant commander was sold on It's A Wrap! sale and auction for US$31.99. [1]