In planetary classification, a class D planetoid is a type of planet. Planets of this type are generally smaller asteroids or moons that are locked into the gravitational pull of a larger planetary body. Class D worlds are usually composed of metals, predominantly nickel, iron and silicate. Bodies of this type generally do not support lifeforms. (ST references: Star Charts, The Worlds of the Federation; Last Unicorn RPG module: Star Trek: The Next Generation Core Game Book)
- This classification was listed as class I as described in ST reference: Star Trek Maps, although the same chart was reprinted by Pocket Books in The Worlds of the Federation with the notation corrected.