Unidentified astrophysical spectra are discussed including the diffuse interstellar absorption bands and visible emission bands from the Red Rectangle nebula and the R Coronae Borealis star V854 Cen. Assignments for the Red Rectangle optical emision and complementary diffuse absorption bands are not yet established, but comparison of the spectra allows some constraints on the nature of the carriers to be inferred.An unidentified infrared emission feature observed towards the two Herbig Ae/Be pre‐main–sequence stars HD 97048 and Elias 1, and reported by Tokunaga et al. (Astrophys. J. 380, 452, 1991) to be centered at 3.5325 μm in the latter, is attributed to part of the fundamental vibration‐rotation spectrum of the H3+ molecular ion.