Probasco was a 23rd century Human Starfleet officer assigned to the USS Enterprise as a crewmember. He shared his quarters with Carter and Cadet Nyota Uhura.
During the Enterprise's mission to Hetemit IX, Probasco, along with every other crewmember aboard the ship, were exposed to a light virus that members of the away team picked up while exploring the planet. (SNW: "Ghosts of Illyria")
Probasco was portrayed by Andre Colquhoun.
This character was only named in the source's end credits.