Axions and axion-like particles (ALPs) can have weak couplings to the Standard Model which may be magnified in extreme astrophysical environments, i.e. stars, providing unique and exciting pathways toward observational signatures. In this talk, I will discuss the novel idea of how axion production at the galactic stellar population level can manifest in particularly powerful probes for axion physics. In particular, I will highlight our various searches for axions coupled to photons and electrons in the summed galactic stellar populations of galaxies such as the M82 starburst galaxy and the M87 central galaxy of the Virgo cluster, which can then convert to detectable hard X-rays via galactic magnetic fields. Using the NuSTAR telescope, we find no evidence for axions and set stringent constraints on the axion-photon coupling, as well as the combined axion-electron axion-photon coupling. I will then discuss further extensions of these ideas, such as with compact objects, and then conclude with ongoing work and prospects using other production mechanisms or other stellar environments which may also push the boundaries on axion parameter space.