90482 Orcus objects with a similar size and orbit to that of Pluto are named after underworld deities. Accordingly, the discoverers suggested naming the object after "Orcus", the Etruscan god of the underworld and punisher of broken oaths. He was portrayed in paintings in Etruscan tombs as a hairy, bearded giant. The name was also a private reference to the homonymous Orcas Island, where Brown's wife Diane had lived as a child and that they visit frequently. On March 30, 2005, Orcus's companion, Vanth, was named after a winged female demon of the Etruscan underworld. She could be present at the moment
90482 Orcus relatively large satellite (Vanth, see below) may change them considerably. The absolute magnitude of Vanth is estimated at 4.88, which means that it is about 11 times fainter than Orcus itself. If the albedos of both bodies are the same at 0.23 then the size of Orcus is about , and the size of Vanth is about . The ALMA submillimeter measurements taken in 2016 showed that Vanth has a relatively large size of with albedo of about 8% while Orcus' has a slightly smaller size of 910 km. Using a stellar occultation by Vanth in 2017, Vanth's diameter has