* "The Shire" for the hobbits who live there: "The Shire was a peaceful place, far from the troubles of the world." Here, "The Shire" represents the hobbits and their way of life.
* "The Company" for the dwarves and hobbit who are on the quest: "The Company had to travel through dangerous forests and mountains." This refers to the group of adventurers as a whole.
* "The Mountain" for the dragon Smaug: "The Mountain was a fierce and powerful creature." This uses the dragon's dwelling place to represent the dragon itself.
* "The Elvenking's Hall" for the Elvenking: "The Elvenking's Hall was a place of beauty and mystery." This substitutes the location for the being it represents.
It's important to note that while these are examples of metonymy in the sense of using a related term, they are not necessarily examples of literary metonymy used for stylistic effect, as they may simply be convenient ways of referring to these elements within the story.
Do you have any other specific examples from The Hobbit that you'd like to discuss?