"Obsession" is the thirteenth episode of the second season of the American science fiction television series Star Trek.
The being appears and attacks two of the members of the security team but Ensign Rizzo disobeys Kirk's order and does not fire his phaser; even as Kirk again orders Rizzo to fire, he just stands there and is also attacked, but is the lone survivor, dying in sickbay after being returned to the ship.
While the Enterprise crew fails to find the creature using shipboard sensors, Kirk sends a second landing party with five security officers and himself, again warning the men to fire full phaser.
Back on the ship, when Kirk learns that security officer Garrovick hesitated to fire his phaser upon the creature, he relieves the ensign of his duties and confines him to quarters.
Spock points out to Kirk that, since the creature cannot be harmed with conventional weapons, the captain has nothing to regret about his earlier encounter.
Spock, after forcing Garrovick to leave, tries to shut it out, and is enveloped, but his copper-based green blood repels it.
[1] When director Ralph Senensky left to observe the Jewish holiday of Yom Kippur, producer John Meredyth Lucas took his place for a few hours, making this his directorial debut for the series.
Paskey was one of the core group of regular Star Trek extras and appeared in almost every episode, including the second pilot "Where No Man Has Gone Before", until he left the show in the middle of the third season.