Ulysse Mérou was the main protagonist of the French novel La Planète des singes. He was a journalist and a friend of Professor Antelle. He accompanied Antelle and his colleague Arthur Levain on a mission to the giant red sun Betelgeuse. On the nearby planet of Soror, they encountered a tribe of primitive humans, and Ulysse met the female, Nova.
After Ulysse was captured by the intelligent apes that dominated the planet, Ulysse was interned in the Institute for Advanced Biological Study. While held captive as a test subject in the study of man, Ulysse made many attempts to prove his intelligence by mimicking Zaius and displaying his ability to speak the simian language.
Later Zaius paired the Earthman with the Sororian woman in a study of sexual selectivity. When the Earthman refused to engage in relations with her, Zaius replaced her as the designated mate to Ulysses's neighbor. She was returned to him and spared the humiliation when Ulysses finally responded in the manner of a savage man.
With pride and defiance Ulysse passed each test the apes thought-up. He was eventually paired with Nova as her mate, but was still regarded as a highly intelligent animal.
He befriended two chimpanzees, Zira and her fiance Cornélius who help him bring his case to the Grand Council to free him from captivity. After he became a free man, he stayed with the institute, acting as a collaborator in the study of man.
During his time on Soror, Ulysse delved in learning the true origins of the simian civilization and the primitive men. He traveled with Cornelius to a dig-site where a great ancient city was unearth. It contained common articles current in modern day simian society, however apparently it was home to a race of civilized men.
It is later revealed that during his intimacy with Nova, he impregnated her, lowering his standing in the eyes of the apes. Later he attended a ground-breaking experiment by a young chimpanzee scientist, who discovered a way to reawaken the memory of the human species. He was horrified to learn of the regression of the human race and the subsequent rise of the apes on Soror.
Ulysse was ultimately forced to escape back to Earth along with Nova and their newborn son Sirius from the alien ape planet. While he was reluctant to abandon Soror and its his fellow men to their fate, his two chimpanzee friends convinced it was in his best interest and family. Upon his return, he discovered that Earth had meantime been taken over by apes too, thus forcing his family to once again flee into space. His first-person journal (which formed the narrative of the book) was left floating idly through interstellar space in a cheap glass bottle, to be found by space-travellers Jinn and Phyllis.
- The character of Ulysse Mérou inspired 'George Taylor' (originally 'John Thomas'), the protagonist of the movie adaptation, Planet of the Apes. Taylor's fate remained largely unchanged, except that in the original book he was a journalist accompanying the mission, rather than its leader; and he ultimately escaped back to Earth from an alien ape planet and discovered that Earth had meantime been taken over by apes too, rather than discovering the alien planet was actually Earth.