Metabolism is an essential component of leukocyte biology, as circulating cells must adapt their metabolic architecture to maintain energy homeostasis and function in the diverse tissue environments they enter. Metabolism therefore represent a potential therapeutic target in many disease states. Neutrophils are the most abundant leukocyte in human blood and are vital for the defence against bacterial and fungal pathogens. However, their activity must be tightly regulated, as inappropriate neutrophil responses damage host tissues and can be detrimental in cancer and inflammatory diseases. Despite their importance, neutrophils are often considered to be a homogenous and simplistic cell subset completely dependent on glucose and unable to undergo metabolic adaptation. However, my work has identified immature neutrophil subsets with enhanced mitochondrial metabolism which are elevated in cancer and severe infectious challenges such as malaria and COVID-19. My ongoing work is investigating neutrophil heterogeneity, with a particular interest in how the metabolism of different subsets alters their effector functions and impact on disease severity. It is my goal to establish myself as an independent researcher, investigating the increasing complexity of neutrophil biology.