The majority of known hadrons in the low-energy QCD spectrum are resonances observed in multi-particle scattering processes. First-principles determinations of the properties of these unstable hadrons are a crucial goal in lattice QCD calculations. Significant progress has been made in developing, implementing, and applying theoretical tools that connect finite-volume lattice QCD quantities to scattering amplitudes, enabling determination of masses and widths of various hadronic resonances. In this talk, I will discuss recent advances in lattice QCD studies of meson-baryon resonances, including the Delta(1232) and Lambda(1405) resonances, as well as three-hadron resonances such as the doubly-charmed tetraquark.