Mitochondria and aging are fast becoming two of the most paired terms in biology. As a crucial nexus for the cell, mitochondria are involved in numerous essential aspects of cell function, from energy production via the respiratory chain to steroid biosynthesis, heme assembly, pyrimidine biosynthesis, the tricarboxylic acid cycle, and apoptosis. Mitochondria are also the main producers of reactive oxygen species within the cell. Theories about aging have revolved around mitochondria for decades, but it is only in the past few years that animal models have started to give significant insights into mitochondria-mediated pathophysiology that might be intimately associated with aging. This review will highlight several new animal models of mitochondrial dysfunction in the context of aging.