There are expected to be 10^7 - 10^9 isolated stellar-mass black holes (BHs) in the Milky Way, constituting the majority of the Galactic BH population. However, while there are several dozen BH binary systems known, there is currently only one confirmed isolated BH. Finding isolated BHs is needed to understand the full population of Galactic BHs, which are important to understanding a broad range of other astrophysics: from the evolution and death of massive stars, to binary interactions, mergers, and disruptions, to providing context for the population of merging BHs found via gravitational waves.