Bensen
Bensen was a Starfleet security officer stationed on board the USS Enterprise during the 2260s.
In 2268, he and Bardoli were part of a landing party led by Captain Kirk that was searching for the dikironium cloud creature on Argus X. (TOS: "Obsession")
Later that year Bensen was called to the transporter room where kept his phaser trained on Jojo Krako when the latter beamed aboard the Enterprise. (TOS: "A Piece of the Action")
Bensen was played by an unknown actor. Some closed-captioning transcripts suggest the name "Swensen" for this character, rather than "Bensen."