Lightkeeper Grahl is a unique grahl found in The Elder Scrolls III: Bloodmoon.
It is a sort of large Ice-troll covered in fur and spikes, with long clawed limbs. It can be found inside the Halls of Penumbra and must be confronted during the quest "The Ritual of the Sun." It is a very powerful, but very slow enemy. After being killed, it drops the Flaming Eye of the Lightkeeper.
The Skaal send the Nerevarine to defeat the Lightkeeper Grahl, so the sunshine's mystical powers would be restored on Solstheim.