The subject of this article originates from non-canonical sources. To find out about what is considered "canon" see LOTR:Canon.
During the time when the War of the Ring began when the One Ring had awoke and was ready to return to his rightful master Sauron, Firnmereth was among the elves that refused to leave Middle-earth and prefer to fight against the enemies of Mordor. Unlike the War of the Last Alliance that happened at the final year of the Second Age and the beginning of the Third Age, Firnmereth accompanied Haldir of Lórien to the old fortress of Helm's Deep where they aided King Théoden and his small army in defending the fortress of Saruman's army of 10,000 Uruk-hai that were tasked by their leader to destroy the people of Rohan. To prevent such atrocity, Firnmereth and kis kin were stationed on top of the Deeping Wall. As the Uruk-hai prepared to lay siege, Firnmereth loaded his bow and killed a number of Uruks throughout the battle. However, he was among the elves that were killed in the battle, but his life along with those that fought and defended the fortress would be honored by King Théoden for defending Rohan and its people.
- The Two Towers (film) (First appearance)
- Firnmereth is not featured in the book.