Mitochondria are vital organelles that produce energy and regulate cellular metabolism. While primarily known for generating ATP through oxidative phosphorylation, recent research highlights their broader influence on biological processes. Beyond energy production, mitochondria shape organismal fitness, adaptation, and life-history strategies by balancing metabolic efficiency, reactive oxygen species (ROS) production, and heat generation. These mechanisms affect performance, ecological interactions, and evolution. Now seen as dynamic regulators rather than mere energy producers, mitochondria integrate multiple metabolic pathways to influence physiology from the cellular to the organismal level. This expanded understanding has advanced ecology and evolutionary biology, offering insights into how organisms adapt to energetic demands and environmental pressures. This ‘Joint FEBS/EMBO Lecture Course’ aims to bring together experts from evolutionary biology, molecular biology, and biochemistry to delve deeper into mitochondrial biology. This interdisciplinary platform will expose students and researchers to diverse perspectives, fostering discussions that inspire innovative research. By combining expertise across fields, the series will highlight mitochondria’s multifaceted roles and their profound impact on metabolism, physiology, and evolution. (Thumbnail photo credit: Alexandra Kukat).