Clom, alternatively spelt Klom, was the twin planet of Raxacoricofallapatorius. The inhabitants of both worlds were similar in physical characteristics and were both members of the Raxas Alliance, but despised each other nonetheless. (DW: Love & Monsters, SJA: The Gift)
The "Abzorbaloff" was a native of Clom. (DW: Love & Monsters)
Clom was also sworn on by a Slitheen as "for the love of Clom". (SJA: Revenge of the Slitheen)
Clom was one of the 27 planets "stolen" into the Medusa Cascade, to which the Doctor replied "Who'd want Clom?" Clom was later returned by the Doctor, the Meta-Crisis Doctor and Donna Noble, to its correct place in space and time. (DW: The Stolen Earth / Journey's End)