Materials exhibiting actuation properties in response to external stimuli have been extensively studied owing to their wide range of applications, including soft robotics, the medical industry (artificial muscles and limbs), and energy storage and conversion. Sophisticated material design has led to the development of soft polymer composites exhibiting autonomous locomotion similar to that of living organisms. Liquid crystal elastomers exhibit continuous rolling and oscillation when exposed to consistent light and temperature. In these examples, mechanical energy is extracted through a nearly constant external field, eliminating the need for the on-off cycling of the light or heat source. Polymer composites are materials that function as external field-response actuators owing to their high flexibility, which enables facile deformation. Recent developments in crystal engineering have revealed the possibility of endowing organic crystals, which were previously considered rigid, with actuation properties. Elastic crystals that can be reversibly bent like elastomers while maintaining their crystallinity have also been reported; these materials are considered promising materials for highly durable and flexible optoelectronic and magnetic devices. Reports on elastic crystals exhibiting actuation in response to light, chemicals, and temperature underscore the diversity of the operating principles of actuators prepared from molecular crystals. However, the extraction of energy from a constant external field, as demonstrated in polymer composites, is rarely observed in organic crystals and remains a challenging endeavour. Most reported crystal-based actuators require fluctuating external fields, such as the on-off cycling of a light source or heater, for continuous motion. The conversion of heat, the lowest grade of energy, into kinetic energy is notably more challenging than the conversion of light owing to the lack of established design criteria for thermal conversion.