Ecofascism is a term which is used to describe individuals and groups which combine environmentalism with fascist viewpoints and tactics. Originally, the term "ecofascist" was considered an academic term for a hypothetical type of government which would militantly enforce environmental measures over the needs and freedoms of its citizens.

In non-academic circles, the term "ecofascist" was originally used as a slur against the emerging environmental movement from the 1970s onwards, with André Gorz speaking of eco-fascism as early as 1977 to characterize (feared) forms of totalitarianism based on an exclusively ecological orientation of politics. However, since the 2010s, a number of individuals and groups have emerged that either self-identify as "ecofascist" or have been labelled so by academic or journalistic sources. These individuals and groups synthesise radical far-right politics with environmentalism and will typically advocate that overpopulation is the primary threat to the environment and that the only solution is to completely halt immigration, or at their most extreme, actively commit genocide against minority groups and ethnicities. As environmentalism has become more and more mainstream in recent decades, many far-right political parties have experimented with adding green politics to their platforms, while since the 2010s a number of terrorists internationally have cited ecofascism as their motive.