In this Special Issue, a wide range of topics are covered, including the design, fabrication, characterization, packaging, and system integration or final applications of miniature actuators, ranging from the centimeter down to the micrometer scale. The main focus of the issue is miniaturization, irrespective of the materials employed or the device principle followed. This Special Issue is a collection of 11 excellent research papers published in Actuators, showcasing and discussing new advances in the field of miniaturized and micro-actuators.