For those who don't know the author, this essay is by the great, late British historian Tony Judt. He frequently wrote about post-war European history and, as a former Zionist, was a well-known and sometimes controversial critic of Israel.
Not to be pendant in, but it depends on what you mean by critic. Max Weber and Erich Fromm were critics of Marx and Freud who agreed with much of what they had to say. Kant's "Critique of Pure Reason" is...well it's many things but it advocates rationality and a marriage of pure reason with experience. Ann Coulter is a critic of the Obama administration and liberalism in general.
