The human overpopulation currently being witnessed is causing severe problems to both the planet Earth and humanity itself (i.e. climate change, environmental degradation, resource depletion, mass species extinction, political instability, extremism, poverty, forced migration, not to mention a major obstacle to achieving the Sustainable Development Goals). Because the issues presented by human overpopulation tend to be seen as a politically incorrect topic, they are largely ignored in the public and political domains, despite being identified as important by many great thinkers in recent history. Among them, Malthus and Marx gathered the largest following. The goal of this presentation was to highlight and compare the Malthusian and Marxist approaches, and neo-Malthusian and neo-Marxist approaches respectively, and then discuss the possibilities to solve these problems.