"The Sorcerer's Stone! Of course -- the Elixir of Life! But I don't understand who --"
"Can you think of nobody who has waited many years to return to power, who has clung to life, awaiting their chance?" ... ...
I think 'nobody' here refers to Voldermort. I don't understand why 'nobody' is being used in this context. I figure it might mean the sense: a person of no influence, authority, or importance. But I think Voldermort isn't that kind of person. On the contrary, he meant a lot to all the people in the book. Otherwise, 'anyone' or 'anybody' looks more appropriate for this context in my opinion.
-- Excerpted from Harry Potter.