Overview: 

One of the last great unknowns in our history of the Universe is when and how the first galaxies emerged after the Big Bang. These galaxies transformed the cosmos --  they illuminated the invisible scaffolding of dark matter that underpins the Universe, they ionized the intergalactic reservoirs of hydrogen, and they synthesized the elements that would one day seed life on Earth. Thanks to JWST, these enigmatic galaxies are finally coming into view. In this talk I will present early JWST results on these systems, and preview upcoming programs I am leading. I will discuss: (i) emerging constraints on the nature of the first galaxies, with a focus on the puzzling abundance of remarkably luminous galaxies at extraordinarily early times; (ii) outstanding questions around how these early galaxies reionized the Universe (e.g., was reionization driven by numerous faint galaxies, or by rare, bright ``oligarch" galaxies?), and the pathway to settle them with JWST.