|Continuity||La Planète des Singes|
|First Appearance||La Planète des Singes|
|Last Appearance||La Planète des Singes|
Mi Zaïus was a leading orangutan scientist on the ape-dominated planet of Soror, the title "Mi" denoting a rank of honour. The head of the Research Institute, he was informed by Zira that she had discovered a human who was capable of thought, and even of speech. Zaïus, who did not believe the fact that man could have a soul or a spirit, dismissed her claims as nonsense, but was discredited when Ulysse Mérou made a convincing address to the ape masses.