Soft robotics technologies are paving the way toward robotic abilities which are vital for a wide range of applications, including manufacturing, manipulation, gripping, human–machine interaction, locomotion, and more. An essential component in a soft robot is the soft actuator which provides the system with a deformable body and allows it to interact with the environment to achieve a desired actuation pattern, such as locomotion. This Review article aims to provide researchers interested in the soft robotics field with a reference guide about the various state-of-the-art soft actuation methodologies that are developed with a wide range of stimuli including light, heat, applied electric and magnetic fields with a focus on their various applications in soft robotics. The underlying principles of the soft actuators are discussed with a focus on the resulting motion complexities, deformations, and multi-functionalities. Finally, various promising applications and examples of the different soft actuators are discussed in addition to their further development potential.