"Man once again faces the war for the dawn, which has been waged since time began. On one side is the Lord of Light, the Heart of Fire, the God of Flame and Shadow. Against him stands the Great Other, whose name may not be spoken. The Lord of Darkness, the Soul of Ice, the God of Night and Terror."
―Thoros of Myr

The Great Other is the antithesis to R'hllor (The Lord of Light), In the A Song of Ice and Fire novels,

His true name is forbidden to be said.

About Edit

Followers of R'hllor believe that there are only two gods, R'hllor and the Great Other, who wage an eternal war over the fate of the world.

All forces of darkness, cold, and death are believed to be servants to the Great Other.