Axions are among the best motivated candidates for dark matter. Their existence would subtly alter the processes within stellar interiors, imprinting characteristic signals in astrophysical observations. Observations with existing X-ray telescopes have already begun to exploit this connection, placing leading constraints on axion dark matter through targeted observations of the Sun, neutron stars, and galaxy clusters. In this talk, I will describe how X-ray telescope technology, pioneered for astronomy, is now being purpose-built for axion searches in the laboratory. I will present the International Axion Observatory (IAXO), a solar observatory that will deliver leading sensitivity to axions and axion-like particles across a wide mass range. I will discuss the novel X-ray optic being developed for IAXO, including its unique design requirements, large-area hybrid configuration, and anticipated performance, highlighting how decades of innovation in X-ray astronomy are now being brought to bear on one of the most compelling open questions in fundamental physics.