The hypothalamus-pituitary axis plays a crucial role in endocrine regulation and energy homeostasis. This study employed single-cell RNA sequencing and whole genome sequencing (WGS) to investigate pituitary neuroendocrine tumors (PitNETs) and hypothalamic tanycytes, aiming to elucidate their molecular characteristics and functional dynamics. In PitNETs, we identified GATA2 as a potential superior marker for non-secreting tumors, observing a strong negative correlation with gonadotropin expression. TNFRSF4 (OX40) emerged as a promising immunotherapy target, predominantly expressed on endothelial cells in the tumor. Mutational signature analysis revealed a prevalence of SBS5 across age groups, suggesting age independent genomic instability mechanisms. A rare KMT2D mutation was identified in a genetically complex PitNET, expanding the spectrum of potential genetic drivers. For hypothalamic tanycytes, we developed a novel pseudospatial analysis approach, leading to the reclassification of α1, α2, and β1 tanycytes as a ”continuum parenchymal tanycyte group.” Fasting-induced transcriptional changes were observed, particularly dorsal-to-ventral shifts in lipid metabolism and neuron interaction genes, indicating functional plasticity in response to metabolic challenges. These findings provide new insights into PitNET biology and tanycyte function, highlighting the complex interplay within the hypothalamus-pituitary axis. Our results suggest potential new diagnostic markers and therapeutic targets for pituitary tumors, while also advancing the understanding of hypothalamic regulation of energy balance. This work underscores the need for integrated approaches in studying neuroendocrine systems and may inform future strategies for managing endocrine and metabolic disorders.