Julian Muñoz is a theoretical astrophysicist, working at the interface of cosmology and astronomy. His best-known work is on 21-cm cosmology and dark matter. He uses techniques ranging from pen-and-paper calculations to computer simulations to confront his theories to cosmological observations. In particular, Julian is an expert in the epochs of cosmic dawn and reionization, when the first stars in the universe formed, which he uses to extract new insights on the nature of the dark sector of our universe. His past work also covers the large-scale structure, cosmic microwave background, and fast radio bursts.