The West Siberian Basin is the largest physical hydrocarbon basin in the world and one of its most prolific. It has proven reserves of 146 billion bbl of oil and more than 1600 TCF of gas. It contains 107 giant fields, 1 mega giant, 10 super giants, and 9 new giants discovered since 2019. Multiple source rocks and reservoirs span Paleozoic through Cretaceous age strata. Structural traps are abundant, many of which have enormous aerial extent. Stratigraphic architecture resulting from multiple transgressions and regressions allows additional combination and stratigraphic trapping.  The rich Mesozoic petroleum systems overlie a complex assemblage of deeper Paleozoic basins, Hercynian accreted terranes, and Permian–Triassic rifts. A northern triple junction linked the basin northwestward into the Kara Sea and northeastward to Yenisey-Khatanga trough. The current sag basin developed in the Early Jurassic and persisted until regional uplift in the Oligocene. Strike-slip faults developed along many terrane boundaries, particularly within and near the Triassic rifts, forming several giant fields.  We provide a historical perspective on exploration history, basin evolution, and some unresolved questions that might lead to new, deeper potential in older areas. The future exploration potential is huge, with conventional plays focused on the Yamal Peninsula and more undrilled giant structures in the Kara Sea. Reserve growth in older fields and new stratigraphic traps offer additional potential as three-dimensional seismic data and integrated studies unlock potential in the more mature provinces. Lastly, underexplored Paleozoic and Neoproterozoic plays exist on the southern fringes of the basin.