Understanding the nature of dark matter is one of the major goals of modern physics.   The abundance and density profiles of dark matter halos depend directly on dark matter particle physics. Strong gravitational lensing enables a direct measurement of these properties for halos at cosmological distances, without requiring halos to contain any baryons at all and thus provides a unique and powerful way to probe the nature of dark matter. I will present our recent results using strongly lensed quasar narrow-line emission to constrain the density profiles and mass function of dark matter halos and to provide some of the strongest constraints to date on warm-dark matter, self-interacting dark matter, and fuzzy dark matter models. I will also present new results from our ongoing JWST survey to measure strongly lensed quasar dusty torus flux ratios. I will conclude by discussing future prospects for strong gravitational lensing in the era of upcoming large surveys and the next generation of 30 meter class telescopes.