Chthonian planet	An extrasolar planet that orbits close to its parent star. Most Chthonian planets are expected to be gas giants that had their atmospheres stripped away, leaving their cores.
Carbon Planet	A theoretical type of terrestrial planet that could form if protoplanetary discs are carbon-rich and oxygen-poor.
City Planet	A hypothetical type of planet where all of its surface is urbanized.
Coreless Planet	A theoretical type of planet that has undergone planetary differentiation but has no metallic core. It is not the same as a hollow Earth.
Desert Planet	A theoretical type of terrestrial planet with very little water.
Gas Dwarf	A low-mass planet composed primarily of hydrogen and helium.
Gas Giant	A massive planet composed primarily of hydrogen and helium.
Helium Planet	A theoretical type of planet that may form via mass loss from a low-mass white dwarf. Helium planets are predicted to have roughly the same diameter as hydrogen-helium planets of the same mass.
Ice Giant	A giant planet composed mainly of 'ices'- volatile substances heavier than hydrogen and helium, such as water, methane, and ammonia-as opposed to 'gas' (hydrogen and helium).
Ice Planet	A type of planet with an icy surface and consist of a global cryosphere.
Iron Planet	A type of planet that consists primarily of an iron-rich core with little or no mantle.
Lava Planet	A theoretical type of terrestrial planet with a surface mostly or entirely covered by molten lava.
Ocean Planet	A theoretical type of planet which has a substantial fraction of its mass made of water.
Protoplanet	Protoplanets are large planetary embryos that originate within protoplanetary discs and have undergone internal melting to produce differentiated interiors. They are believed to form out of kilometer-sized planetesimals that attract each other gravitationally and collide.
Puffy Planet (Interstellar planet)	Gas giants with a large radius and very low density are sometimes called "puffy planets" or "hot Saturns", due to their density similar to or lower than Saturn's.
Silicate Planet	A terrestrial planet that is composed primarily of silicate rocks. All four inner planets in our Solar System are of silicate type.
Terrestial Planet	A terrestrial planet, telluric planet or rocky planet is a planet that is composed primarily of carbonaceous or silicate rocks or metals.