Mitochondria are dynamic organelles essential for cellular health, with their structure influencing function. Recent studies reveal that mitochondria exhibit diverse shapes, such as donuts, megamitochondria (MGs), and nanotunnels, which vary across tissues and in response to disease or stress. These shapes are regulated by mitochondrial dynamics, including fusion and fission, and are influenced by interactions with other organelles like the endoplasmic reticulum (ER). Advanced imaging techniques, such as cryo-electron tomography, allow for detailed visualization of mitochondrial structures and their associated protein complexes. Mitochondrial morphology is crucial for maintaining bioenergetics and cellular homeostasis, and alterations in shape are linked to mitochondrial dysfunction in diseases. For example, donut-shaped mitochondria are associated with stress and may indicate disease states like Alzheimer's. MGs, which are larger than normal mitochondria, are observed in conditions such as non-alcoholic fatty liver disease. Nanotunnels, formed by incomplete fission, are implicated in mitochondrial transport and may be linked to mtDNA mutations. The cristae, internal structures of mitochondria, also play a key role in mitochondrial function, with their shape and organization influenced by the mitochondrial contact site and cristae organizing system (MICOS) complex. Understanding mitochondrial structure and dynamics is essential for developing therapeutic strategies to manage mitochondrial diseases. Future research will benefit from advanced imaging and computational tools to better characterize mitochondrial phenotypes and their roles in health and disease.Mitochondria are dynamic organelles essential for cellular health, with their structure influencing function. Recent studies reveal that mitochondria exhibit diverse shapes, such as donuts, megamitochondria (MGs), and nanotunnels, which vary across tissues and in response to disease or stress. These shapes are regulated by mitochondrial dynamics, including fusion and fission, and are influenced by interactions with other organelles like the endoplasmic reticulum (ER). Advanced imaging techniques, such as cryo-electron tomography, allow for detailed visualization of mitochondrial structures and their associated protein complexes. Mitochondrial morphology is crucial for maintaining bioenergetics and cellular homeostasis, and alterations in shape are linked to mitochondrial dysfunction in diseases. For example, donut-shaped mitochondria are associated with stress and may indicate disease states like Alzheimer's. MGs, which are larger than normal mitochondria, are observed in conditions such as non-alcoholic fatty liver disease. Nanotunnels, formed by incomplete fission, are implicated in mitochondrial transport and may be linked to mtDNA mutations. The cristae, internal structures of mitochondria, also play a key role in mitochondrial function, with their shape and organization influenced by the mitochondrial contact site and cristae organizing system (MICOS) complex. Understanding mitochondrial structure and dynamics is essential for developing therapeutic strategies to manage mitochondrial diseases. Future research will benefit from advanced imaging and computational tools to better characterize mitochondrial phenotypes and their roles in health and disease.