The Discovery's advanced computer system, known for its human-like traits and complex interactions with the crew, becoming a crucial part of the story's conflict.

Bowman's fellow astronaut on the Discovery mission, who shares a similar routine but remains less explored personally compared to Bowman.

A prominent figure in the early part of the narrative, tasked with overseeing a significant lunar project, and later communicates key information to Bowman.

The leader of a "man-ape" tribe, representing primitive humanity's first steps toward evolution, as seen in the initial section of the story.