Axions are a well-motivated extension to the Standard Model and are among the best candidates to explain dark matter. Their detection is made difficult by the fact that they couple very weakly to particles in the Standard Model. High-energy astrophysical settings host extreme conditions wherein axions may be produced in great abundance. In this talk, I will discuss axion production in the highly magnetized plasma surrounding compact objects, particularly neutron stars. Once produced, axions may re-convert to photons, leading to anomalous emission. Radio observations of nearby pulsars can place stringent constraints on the axion-photon coupling that improve upon existing bounds by orders of magnitude for a range of axion masses. Finally, I will discuss an axion model for the mysterious Fast Radio Bursts (FRBs) observed by several radio missions, including the CHIME experiment, which is co-led by the University of Toronto.