Abstract: Supermassive black holes (SMBHs), typically ranging from a million to billion solar masses, are now known to inhabit the centers of most massive galaxies in our Universe. Unraveling their elusive cosmic origins stands as a critical scientific objective for current and upcoming electromagnetic and gravitational-wave observational facilities, such as the James Webb Space Telescope (JWST) and the Laser Interferometer Space Antenna (LISA). In this presentation, I will discuss my recent research, which involves the development of new cosmological simulations to model the formation of the earliest black holes in the Universe that potentially served as the "seeds" for present day supermassive black holes. Possible candidates for these seeds include the remnants of the first generation of metal free stars called Population III stars, or black holes formed via direct collapse of metal free gas without forming any stars. I will demonstrate how these different formation scenarios for these seeds result in distinct signatures in the early black hole populations, detectable with JWST and LISA. Furthermore, I will outline my near-term research plans, focusing on understanding the future evolution of these black hole populations across cosmic time and their impact on their host galaxies. Finally, I will discuss how this research lays the groundwork for my longer term research vision, which encompasses fundamental questions about our Universe, including the nature of dark energy, dark matter, and the formation and evolution of galaxies.