Been there. Was involved in a telco software project where one person was a genius, a true unicorn. We were in meetings where some of his insight and perspective left us scratching our heads in amazement. Yet he was the most destructive co-worker I've ever come across.

He never did anything. He would belittle others if they didn't grasp things. He would see a well-layout project plan and laugh and say that he could do it in a weekend, and management would listen because of his intellect and dominating presence. Every request for him to actually do any work was met with a 'too busy' answer, yet he would berate others for not meeting schedules.