Longo was a Human Starfleet officer who was assigned to the USS Enterprise-D in 2364. In that year, Longo was a lieutenant. He began playing Parrises squares as an ensign.
He was among the group of Starfleet officers who visited the Bandi shopping mall at Farpoint Station during the Enterprise-D's visit. Later he passed the sickbay aboard the ship. (TNG: "Encounter at Farpoint")
He was also a member of the Parrises squares team of the Enterprise-D and prepared for a match together with Worf, Tasha Yar, and another female crewmember against the Starbase 74 team. (TNG: "11001001")
Wearing a skant uniform, he was working on a computer panel in a corridor and was passed by Captain Picard, Commander Riker, and Admiral Gregory Quinn. (TNG: "Conspiracy")
Longo was played by background actor Brad Phillips who received no credit for his appearances.
The Parrises squares case he was carrying included information on his rank and surname. It reads, "Ens. Longo".
He was named after the first season property master Joe Longo