Purple air-stable crystals of Ir₈Se₄₀Br₁₀ were obtained by reacting Ir in an excess of Se and SeBr₄ at 300°C for two weeks. The monoclinic crystal structure [space group P2 ₁/c, a = 1371.9(1) pm, b = 1108.1(1) pm, c = 2058.2(1) pm, β = 106.897(2)° at 296(1) K] consists of uncharged clusters Ir ₈Se₄₀Br₁₀ = (Ir³⁺) ₈(Se₂^2-)(Se₄^2-) ₆(Se₇)₂(Br^-)₁₀. The iridium(III) cations are coordinated octahedrally by selenium and bromide ions. While the oligoselenide anions provide high intra-cluster connectivity, μ₆-η² in the case of Se₂^2- and μ₄-η³ for Se₄^2-, the terminal uncharged Se₇ rings have boat conformation and are η¹-coordinating. About 10% of the Se₇ rings are substituted by Se₆ rings with chair conformation. A similar reaction using SeCl₄ yielded vermillion air-stable crystals of Ir ₂Se₉Cl₆. X-ray diffraction on a single-crystal revealed a tetragonal lattice (space group I4₁/a) with a = 1229.8(1) pm and c = 2365.5(2) pm at 296(1) K. In the Se₉(IrCl ₃)₂ cluster, a crown-shaped uncharged Se₉ ring coordinates two iridium(III) cations as a bridging bis-tridentate ligand. Three terminal chloride ions complete the distorted octahedral coordination of each transition metal atom.