Nokkar
Nokkar was an ancient alien sentinel, a member of the N'Kai race, posted on Easter Island on Earth eons ago to watch over an outpost in an intergalactic war against the Space-Spawn. In centuries past, Nokkar was friends with the humans of Easter Island, who made the Moai statues in his honor. In recent times, however, Nokkar held his vigil alone.
In 1996, the Avalon travellers arrived, and Nokkar mistook the gargoyles for aliens. He subjected Elisa Maza to a mind-cleansing process designed to remove what he believed was alien brainwashing from her mind. It also left her temporarily amnesiac, and she wandered while the sentinel captured Angela and Bronx. Goliath was also captured, and Nokkar explained to Maza what he had done. However, just as he was about to painlessly execute the gargoyles, Elisa regained enough of her memory to stop the sentinel, which in turn convinced Nokkar of the truth of her friendship with them.
Nokkar thereafter has shared his watch with the humans Dr. Lydia Duane, Peter Morwood-Smyth, and Dr. Arnada.
Greg Weisman's Master Plan
Nokkar would have been centrally involved in the events of the Gargoyles 2198 series.