The Duros were a humanoid species native to Duro, a planet located in the Duro sector of the galaxy’s Core Worlds. They had smooth blue-green skin, red eyes, lipless mouths, and long thin noseless faces with green blood. When the Duros experienced high amounts of strain, a kind of oil—which had a highly irritating smell and bad taste—gathered in the sacs along their ribs. This was an evolutionary throwback and defense mechanism, remaining from when the Duros were liable to be eaten by a number of entities roaming Duro. They were related to the similar-looking Neimoidian species, having sufficiently diverged in physical appearance by 15,000 BBY to be distinguished.

The Duros were one of the first cultures to develop hyperdrive-equipped ships, and as such, could be found all over the galaxy and were described as adventurous. A colonial species, they had migrated and adapted to dominate many worlds. After the establishment of the Galactic Empire, Duro became one of the first planets in the Core Worlds to be under Imperial control. Many Duros would become fugitives from their homeworld, and many joined the Alliance to Restore the Republic.