The Hofstadter butterfly—the fractal energy spectrum of a two-dimensional electron ina magnetic field on a lattice—is shown to possess a natural hierarchy parameterized by themetallic means, the roots of x2 = nx + 1. The Harper equation that generates each horizontalslice of the butterfly is mathematically identical to the Aubry—André—Harper (AAH) Hamiltonian at the self-dual critical point V= 2J. Each irrational flux ratio α produces a Cantor-set spectrum with Hausdorff dimension Ds = 1/2.We show that two experimentally significant systems in graphene moiré physics correspondto specific metallic means: (1) the graphene/hBN lattice mismatch (δ= 1.68%) corresponds to metallic mean n = 60, with golden-ratio quasiperiodicity nested inside the n = 60 shell via continued fraction structure [0; 59, 1, 1, 1, . . .]; (2) the magic angle of twisted bilayer graphene (θ= 1.08◦) corresponds to metallic mean n = 53, matching to 0.06%.At golden flux (α = 1/ϕ), the five-band Cantor partition carries Chern numbers +2,−1, +1,−2.The outer pair (+2,−2) annihilates via topological pair annihilation, collapsing five bands to three—the 5→3 mechanism supported by Liu, Fulga & Asbóth (2020). The first three metallic mean discriminants ∆n = n2 + 4 are consecutive Fibonacci numbers (5, 8, 13), forming a Pythagorean triple (√5)2 + (√8)2 = (√13)2 that closes at exactly three spatial dimensions.36 supporting references span Hofstadter spectroscopy, moiré physics, Floquet topology, and metallic mean quasicrystals.