In J.R.R. Tolkien's The Lord of the Rings, the Fellowship is formed in Rivendell.
Rivendell is the Elven refuge founded and ruled by Elrond. Frodo reaches it after being wounded by a Morgul-knife, and representatives of Elves, Men, Dwarves, and Hobbits gather there for the Council of Elrond. The council determines that the One Ring must be destroyed in Mount Doom.
The Fellowship then leaves Rivendell as a company of nine walkers: four Hobbits, two Men, Legolas, Gimli, and Gandalf. Rivendell is also called Imladris in Sindarin. It is distinct from Lothlórien, the woodland realm ruled by Galadriel and Celeborn, which the Fellowship visits later.