Planet Hell was the crew's nickname for a Delta Quadrant world wrapped in corrosive vapour, where Tom Paris and Neelix were stranded together and found themselves nursing a newborn reptilian alien.
The planet appears in the second-season episode Parturition. Voyager, short of food, detects amino acids on a world whose dense atmosphere blocks sensors and transporters, and Janeway sends Paris and Neelix down in a shuttle despite their quarrel over Kes.
The shuttle is forced down, and the two men shelter in a cave from fumes that irritate the skin and lungs. There they find a clutch of eggs, one of which hatches. They keep the infant alive until its mother returns.
In orbit, Voyager fends off an alien ship guarding the nesting ground. The ordeal ends the rivalry between Paris and Neelix. The name echoes the production crew's long-standing nickname for the soundstage used for alien landscapes.