Computational Methodology: QM8 originates from the QM9 data set, containing 134,000 molecules with up to nine heavy atoms. Initially, molecules with high steric strain in their initial geometries, computed using the B3LYP/6-31G(2df,p) method, were eliminated. Subsequently, the data set was narrowed down to molecules containing a maximum of eight heavy atoms (carbon, nitrogen, oxygen, and sulfur), resulting in approximately 21,800 molecules. The geometries for these molecules were assumed to be relaxed, as per the original QM9 data set. Single-point calculations were performed with the TURBO-MOLE program to determine ground (S 0 ) and the lowest two singlet excited states (S 1 and S 2 ). The used methods include long-range corrected TD-DFT (LR-TDDFT) with PBE0 and CAM-B3LYP functionals, and different basis sets (def2-SVP and def2-TZVP), as well as the resolutionof-identity approximate coupled cluster with singles and doubles substitution (RI-CC2) method with the def2-TZVP basis set. A total of 14 "exotic" molecules were excluded due to convergence issues (7 molecules) or negative lowest transition energy, potentially attributed to orbital relaxation.