As others have said, Wormtongue was more of a nickname given to him by people that didn’t like him. Think Ivan the Terrible, Tsar of Russia, or something like that.
In fact, the only people in middle earth who are shown to have surnames are Hobbits and some Men from Bree, where Hobbits and Men live together and is no doubt heavily influenced by Hobbit culture.
As others have said, Wormtongue was more of a nickname given to him by people that didn’t like him. Think Ivan the Terrible, Tsar of Russia, or something like that.
In fact, the only people in middle earth who are shown to have surnames are Hobbits and some Men from Bree, where Hobbits and Men live together and is no doubt heavily influenced by Hobbit culture.