Which galaxies reionized the universe? The top, middle, and bottom panels show groupings of galaxies by M_UV (observed), stellar mass, and halo mass, respectively. The left and center columns are shaded by the relative contribution of each group to the total ionizing budget (﹩{\dot{n}}_{\mathrm{ion}}﹩) as per our two models for ﹩{f}_{\mathrm{esc}}﹩. The right-most column is colored by the relative number-density of each group. The black dotted lines in each panel sandwich the redshift-space when the universe is inferred to go from 90% (z₉₀) to 10% neutral (z₁₀). In the central panel, the reionization budget is essentially a reflection of our predicted UVLF, since ξ_ion does not vary strongly with luminosity and ﹩{f}_{\mathrm{esc}}﹩ is constant, while in the left panel the ﹩{f}_{\mathrm{esc}}﹩ ∝ ﹩{{\rm{\Sigma }}}_{\mathrm{SFR}}﹩ model further down-weights the contribution of faint galaxies. UV-bright and massive sources represented in orange and blue dominate the reionization budget (≳50%–80%), despite comprising ≲5% of the population. This scenario, “reionization by oligarchs,” stands in stark contrast to the canonical “democratic reionization” led by copious faint sources.