Arno Peters (1916-2002) was a German schoolteacher best known for the map projection he promoted, the Gall-Peters projection.
Peters noted that many textbooks and atlases used the Mercator projection for their world maps. The Mercator projection was developed to aid navigation at sea, and so it distorts the sizes of landmasses closer to the poles. In particular, Peters objcted to the fact that Mercator maps greatly exaggerated the size of rich and powerful countries such as the USA, Soviet Union, and Europe, while diminishing the sizes of poorer tropical countries in Asia, Africa, and Latin America. Peters developed a cylindrical equal-area projection -- that is, one that keeps all areas the correct size relative to each other -- which he published in 1974. He later published an atlas based on this projection, with all maps shown at the same scale.
Professional cartographers were widely critical of Peters. They agreed that the Mercator projection is inappropriate for general world maps. However, they pointed out that there were many equal-area projections already in existence (such as the Molleweide and Goode's Interrupted Homolosine), which did not distort the shapes of land areas as greatly as Peters' projection. Moreover, they pointed out that Peters was not even the first to invent his projection -- it had already been published by the Scottish clergyman James Gall in 1855 (hence the modern name "Gall-Peters projection"). Nevertheless, Peters' public advocacy for his projection led to it being adopted by a variety of institutions, and drew much public attention to the way different map projections can distort our view of the world.