Inorganic semiconductors are vital for a number of critical applications but are almost universally brittle. Here, we report the superplastic deformability of indium selenide (InSe). Bulk single-crystalline InSe can be compressed by orders of magnitude and morphed into a Möbius strip or a simple origami at room temperature. The exceptional plasticity of this two-dimensional van der Waals inorganic semiconductor is attributed to the interlayer gliding and cross-layer dislocation slip that are mediated by the long-range In-Se Coulomb interaction across the van der Waals gap and soft intralayer In-Se bonding. We propose a combinatory deformability indicator (Ξ) to prescreen candidate bulk semiconductors for use in next-generation deformable or flexible electronics.