The hypothalamus is a structurally and functionally complex brain region that controls organismal homeostasis by mediating endocrine, autonomic and behavioral inputs/outputs. These functions are exerted by extremely diverse neuronal subtypes, which are assembled into multiple hypothalamic nuclei and frequently featured by different neuropeptides and neurotransmitters. Single-cell analysis of developing, adult and aged hypothalamus have been providing deep insights into the specification and function of different neuronal subtypes throughout the life course of animals and human beings.