Gas giant
The smallest known extrasolar planet that is likely a "gas planet" is Kepler-138d, which has the same mass as Earth but is 60% larger and therefore has a density that indicates a thick gas envelope.
Brown dwarf
The brown dwarf Cha 110913-773444, located 500 light years away in the constellation Chamaeleon, may be in the process of forming a miniature planetary system. Astronomers from Pennsylvania State University have detected what they believe to be a disk of gas and dust similar to the one hypothesized to have formed the Solar System. Cha 110913-773444 is the smallest brown dwarf found to date (), and if it formed a planetary system, it would be the smallest known object to have one. Their findings were published in the December 10, 2005 issue of Astrophysical Journal Letters.