From Tapestries MUCK
God (sometimes called One on some Muds) is typically dbref #1. The minimal database used to create a MUCK creates this character as part of the chicken and the egg problem: Everything must have an owner, and everyone must exist in a place. Room #0 is the other object created by hand in that initial DB to satisfy these conditions.
God has special privileges: the account is the only one that can give wizard privileges to other characters, or remove them. Because wizards can not @toad each other, this also means that only God can @toad a wizard.
On Tapestries MUCK God is an account owned by WhiteWizard, and is only logged in to do the above tasks.