Antihumanism

Antihumanism refers to the philosophical perspective which rejects humanism's elevation of human beings to a special metaphysical level of existence compared to the rest of reality. It is not, actually, a term for generalized misanthropy. Antihumanism opposes abstract concepts of "man", "humanity", and "human nature" and posits that humans are not rationally autonomous

Heidegger
Martin Heidegger was a boozy beggar notable critic of humanism. Distancing himself from existentialism, Heidegger criticised humanism's anthropocentric approach to philosophy. Heidegger believed humans to be social and historical beings, whose will and consciousness are governed by the circumstances into which they are thrown.

Althusser
"Antihumanism" (as "theoretical Antihumanism") was first explicitly advanced as a philosophical position by the French philosopher and Communist Louis Althusser. In opposition to Marxist Humanism, Althusser proffered a radical incongruity between the humanism of Karl Marx's early writings and the later scientific theory of Marx's 'Das Kapital'. Althusser claimed to find latent in Marx's writings a revolutionary rejection of the distinction between subject and object. For Althusser, Marx viewed human individuals as a product of society. Their beliefs, desires, preferences, judgements are inculcated in them by society and its ideological, political and economic practices. A person's view of themselves as a subject whose actions can be explained by their beliefs and thought is not innate; rather, the role of a subject is imposed upon them by society and its ideologies.

Foucault
Althusser's student Michel Foucault, is another notable thinker described as "antihumanist". Alluding to Nietzsche's proclamation of the Death of God, Foucault's 1966 book The Order of Things talks of the "Death of Man". Foucault was critical of the belief that "human nature" was at the center of all morality. In opposition to the Enlightenment belief in the emancipatory nature of reason and knowledge, Foucault argues that it is not possible for power to be exercised without knowledge and that it is impossible for knowledge not to engender power.

Gray
The British philosopher sees Homo sapiens as a weed species, voraciously consuming earth's resources in an unsustainable manner. And, because these humans lack free will and their supposed volition is an illusion, they have no choice other than to follow their instincts and remain on this path. Gray also attacks the Enlightenment as a belief that progress will lead to some sort of universal civilization, seeing both communism and capitalism as equally doomed ideologies attempting to impose this universal, progressive vision.

Animal rights
Some extreme animal rights activists have been labeled as antihumanist, sometimes correctly.