Designing resilient actuators is an industrial challenge partly because an index of resilience does not exist yet. In this work, several definitions of resilience are analysed based on which an index quantifying resilience for actuators is proposed. This index allows comparing resilience of a wide range of manufactured and biological actuators. The two manufactured actuators chosen as iconic models, a hydraulic cylinder and a bio-inspired McKibben muscle, are shown not to be resilient by design. Differently, two biological actuators likely to be resilient were analysed. The pulvinus resilience index shows that it is partly resilient depending on damage location. The most promising is the skeletal muscle which have been shown to be highly resilient. Finally, the bio-inspired roots of resilience are discussed: resilience may originate from multi-scale structural design.