An Enterprise lieutenant who was in the recreation room in 2266 when Kevin Riley, alone on duty in engineering, was poisoned during the voyage of the Karidian Players.
Lieutenant Matson appears in The Conscience of the King. He is among the off-duty crew in the recreation room when Kevin Riley, banished to a lonely watch in engineering by Kirk, calls up over the intercom to complain about the quiet and ask for company.
Uhura answers by singing Beyond Antares to him over the open channel. While she sings, an unseen hand sprays poison into Riley's glass of milk; he drinks, chokes and collapses, and the listeners in the recreation room hear it happen and raise the alarm that gets him to sickbay in time.
Matson has only a few lines, but the scene is the turning point at which Kirk accepts that someone aboard is killing the last witnesses to Kodos. He was played by David Troy.