arrives at the planet Exo III, from which the last report from archeologist Dr. Richard Korby was transmitted five years before. Korby allows Kirk and Nurse Chapel, his former lover, to beam down. There they discover that Korby has been working with machinery left behind by the previous inhabitants of the planet, allowing him to become a master of robotics. But his extraordinary behavior, and requests for the resources he will need to continue his work, lead Kirk to believe he may have gone insane.
- Bald of Evil: Ruk.
- Brain Uploading: Dr. Korby can create a robotic clone of a person where the consciousness is preserved in the robot body and in fact has uploaded himself to a robotic body.
- A Day in the Limelight: For Chapel.
- Cybernetics Eat Your Soul: This seems to be the case here, but it's unclear. For example, when robo-Korby tries suggesting tests to prove that he's really the same old Korby, he can't think of anything not obviously robotic in nature, yet this fact seems to make him upset. In general, certain elements of humanity seem impossible for Korby's robots, but it's hard to tell.
- Everything's Better with Spinning: For some inexplicable reason, the android duplicator requires spinning like a carousel.
- Fantastic Racism: Kirk focuses on Spock's status as a half-breed when his mind was being copied for the android. Spock does admit to some dismay that Kirk would use such an unsophisticated phrase, but it's not clear if his feelings were otherwise hurt.
- Half-Human Hybrid: Spock, of course, is half-human, half-Vulcan. This becomes relevant when Kirk tricks his clone into calling Spock a Half-Breed.
- Hey, It's That Guy!: You rang, Captain Kirk?
- Holy Backlight: While traipsing through the creepy cavern, they expect Dr. Korby to appear, but it's just Dr. Brown making a dramatic entrance.
- Ironic Name: Andrea means "Man". Specifically, it refers to a male as opposed to a human, making it doubly ironic.
- Living Legend: Dr. Korby, the "pasteur" of archeological medicine, famous for his translation of the medical records from the Orion ruins, which are "required reading" at Starfleet Academy.
- Meaningful Name: Andrea the android.
- Ms. Fanservice: Andrea.
- Murder Suicide: The fate of Andrea and Korby
- Precursors: The "Old ones", an ancient civilization left Ruk and other technologies in the underground caverns.
- Red Shirt: Notable for being the first episode where the trope is fully in play, trope name and all: Two red-dressed security-officers are killed off within minutes after Kirk has them beamed down to provide backup.
- Reluctant Mad Scientist: Dr. Korby would cure humanity of all it's problems if only he could change all humans to robots. Multiple times he tries to convince a non-cooperative Kirk of his vision.
- Robot Master: Korby.
- Robotic Reveal: No fewer than four times, if we count both visual instances (Dr. Brown and Korby) and verbal ones (Ruk and Andrea).
- Sexy Backless Outfit: Andrea's outfit covers even less of her back than it does of her front.
- Something They Would Never Say: Kirk mentally focuses on a racist insult toward Spock as his robot duplicate is made, leading the otherwise flawless copy to say it to Spock and alert him that something's up.
- Theiss Titillation Theory: Andrea provides the page picture.
- Transhuman: Dr. Korby insists humans would be improved as androids that can be programmed without jealously, greed and hate, no deaths, deformities and even fear replaced with joy.
- Twinmaker: Dr. Korby uses the ancient civilization's technology to clone Kirk as a robot.
- Voice Changeling: Ruk.
- What Is This Thing You Call Love?: Andrea's confusion about love, kissing, etc is understandable when she keeps getting inconsistent instructions.
- What Measure Is a Non-Human?: Averted; the deaths of Andrea and Korby are presented as unequivocally tragic (admittedly, partly because Chapel hadn't even begun to work through her feelings about Korby by that point).