Fenrir is a legendary wolf of Fremennik mythology. He first appeared during the 2016 Winter event, and subsequently appeared every year, up to and including 2019, spawning to the north-east of the golden apple tree.
Fenrir doesn't count as a wolf for Slayer assignments.
When he appears, he is accompanied by smaller versions of Hati and Sköll. Fenrir is invincible until the images have been defeated, with any damage against him being reduced and redirected to the images. He has four special attacks: raining down fiery meteors dealing damage based on the player's current life points, summoning the images of Hati and Sköll, Slaughter, and a howl which puts abilities on a global cooldown for 3.6 seconds and halts channelled attacks and bleeds.
- Like Hati and Sköll, who are based on the Nordic Hati Hróðvitnisson and Sköll, Fenrir is based on the figure of the same name featured in Norse mythology (Old Norse: Fenrisúlfr, often translated as The Fenris wolf). This is in keeping with the image of the Fremennik, who are based heavily on the real-world Norsemen. In Norse mythology, he is the father of Hati and Sköll.
- On release he spawned every 30 minutes. This was changed to every 15 minutes on 19 January 2016.
- Before the 2019 winter event Fenrir's respawn would trigger a global announcement: News: With a howl, Fenrir has appeared! Head to Rellekka and help defeat him!
- Fenrir was aggressive until the 2019 winter event. The images of Hati and Sköll still remained aggressive.