  The origin of dark matter as a thermal relic offers a compelling way in which
the early universe was initially populated by dark matter. Alternative
explanations typically appear exotic compared to the simplicity of thermal
production. However, recent observations and progress from theory suggest that
it may be necessary to be more critical. This is important because ongoing
searches probing the microscopic properties of dark matter typically rely on
the assumption of dark matter as a single, unique, thermal relic. On general
grounds I will argue that non-thermal production of dark matter seems to be a
robust prediction of physics beyond the standard model. However, if such models
are to lead to realistic phenomenology, they must sit in a restrictive
theoretical framework. As we will show, as a consequence of such restrictions,
viable models will result in concrete and testable predictions. Although many
challenges remain, the non-thermal component of such models may offer a new way
to test string theories that are formulated to provide realistic particle
physics near the electroweak scale.
