Genesis was an uninhabited planet located in the Mutara sector.

The planet was created from gaseous matter inside the Mutara Nebula following the detonation of the Genesis Device inside the nebula by Khan Noonien Singh. Shortly after the planet formed, the photon torpedo containing the body of Captain Spock was fired into space over the planet but landed on the surface. The radiation emanating from the planet regenerated his cells. Spock was thus reborn as a child but quickly aged to adulthood.

At first, the planet was a lush, vibrant world with all manner of weather conditions within a few hours walk of each other. However, because Doctor David Marcus had used protomatter in the construction of the Genesis Device, its unstable and dangerous properties caused Genesis to rapidly age and become instable. Spock was rescued moments before the planet exploded.