A Beta III official who operates Landru's absorption chamber but secretly belongs to the underground, saving Kirk and Spock from absorption.
Marplon works for Landru on Beta III, running the equipment used to absorb dissenters into the Body. Unknown to the Lawgivers, he is one of the underground who resist the computer's control.
In The Return of the Archons, Marplon is ordered to absorb Kirk and Spock. He pretends to do so but spares them, letting them feign absorption while they plan to confront Landru. He later guides them toward the computer's hidden location, which allows Kirk to argue it into destroying itself. He was played by Torin Thatcher.