Moon-Watcher
Moon-Watcher is never actually named in the film, but is listed in the credits as the prehistoric ape who embodies the concept of the Monolith kickstarting human evolution. Moon-Watcher is the ape who famously throws a bone into the air that—in one of the most astonishing cuts in film history—instantly transports the audience three million years or so into the future to the point where evolution of the species has allowed mankind to leave his plant and explore the cosmos on their own.
HAL 9000
It is worth noting at this point that none of the human beings in 2001: A Space Odyssey exhibit nearly the typical characteristics that usually define a character as “interesting” to the extent that those characteristics are demonstrated by Moon-Watcher and the movie’s most famous character, HAL. The HAL 9000 is the computer with the deceptively non-emotional monotone human voice that controls all the functions aboard the Discovery spaceship carrying its crew to Saturn.
Dr. Heywood Floyd
Dr. Heywood Floyd is a high level government official who is sent to the moon to after workers there uncover another Monolith similar to the one that invests Moon-Watcher with the intelligence needed to move apes toward their evolution into man. The Monoliths act as sentinels informing the extra-terrestrial intelligence that placed them there of that evolutionary progress. Floyd is on the moon when the Monolith emits the ear-piercing signal that leads the government to their decision to send the Discovery crew to Saturn.
Frank Poole
Frank Poole is one of the astronauts aboard the Discovery as it makes its way to Saturn. As with the other humans, little information is given about Poole’s life. His death outside the environs of the Discovery spaceship will ultimately prove the most interesting thing about Poole…and even that interest is actually directed more toward another character.
Dave Bowman
Bowman is another astronaut aboard the Discovery on the way to Saturn with Poole. The two of them together realize that HAL is not quite the unemotional, benevolently programmed GPS system it appears to be. Believing that they are free to discuss their conspiratorial reaction to this enlightenment if HAL cannot hear what they are saying turns out to be a fatal underestimation of the computer’s ability to read their lips. Once Poole dies, Bowman is left to his own devices find the true purpose of Discovery’s mission to Saturn. Just as Moon-Watcher is the vessel through which the Monolith thrusts humans to their next stage of evolutionary development from ape, so ultimately is Dave Bowman another vessel transporting the evolutionary development of the human species. And yet, Dave Bowman is no more fascinating or psychologically conceptualized than Heywoood Floyd or Frank Poole, or, for that matter, any other of the few minor human characters with whom any of them briefly and prosaically come into contact.
