Notwithstanding the exceptional immense ecological value, the Biodiversity of Buxa Tiger Reserve (BTR) is least explored or projected so far. Given its unique biogeographic nexus and fundamental Bhutan, Assam and rest of North Bengal turns it into a crucial, yet highly vulnerable, conservation priority. This compendium is the first perspective, offering a comprehensive reptiles, 132 hthyofauna and 500+ including extinction tragedy will not only serve as an essential reference handbook for rious stakeholders, scientists, researchers, and students ecology, and environmental science but also help disseminate among the policymakers, public and ecotourists habitat heterogeneity quantified by dependency on the gene flow from ever vivid documentation of unique wealth of BTR in ecological and authoritative scientific baseline for Biodiversity conservation, management, and understanding of the crucial Eastern Himalayan ecosystem. An updated taxonomic and biological account of 1,349 flora, 90 mammals, 13 amphibians, 612 avifauna, 47 entomofauna, including new discoveries through camera trapping, species distribution, population dynamics, complex intra and inter-species interactions within the ecosystem and threat assessment studying conservation biology, about the unique value and fragility of the Buxa ecosystem, fostering a sense of stewardship.