The Fear Lords, or Lords of Fear, are composed of Dweller In Darkness (Who's supposedly their leader), Nightmare, D'Spayre, Lurking Unknown, Nox, Kkallakku and Straw Man. They first gathered together in to the Halls of Fear Dimension, a universe completely separate from the prime reality(616).
Each Fear Lord represents the concept of darkness itself in their respective pantheons/universes/dimensions and even the absolute evil in some cases. They only possess one goal, which is to strike fear into the hearts of every living being in the entire universe and beyond.
The Fear Lords as a team first appeared during Doctor Strange, Sorcerer Supreme #31 - To Stop the Silver Surfer at the end of the issue with Dweller in Darkness explaining his plan of causing an ultimate collapse/catastrophe in the entire Earth to feed upon the despair and fear of the victims. Straw Man didn't agree in following such route and decided to seek the help of the Sorcerer Supreme to stop his comrades from performing this terrible act.
After numerous battles against the members of the team and even some internal conflicts between Nightmare and Dweller for example; Strange was able to defeat them once for all when D'Spayre succumbed in a hard-fought struggle against the master of the mystical arts.