A fundamental question in the theory of matter concerns the nature of different phases, the transitions between them and the associated critical phenomena. The researches of Michael Fisher address many aspects of these basic questions ranging from establishing rigorous theorems for the underlying statistical mechanics through exact analytical and precise numerical solutions for model systems, dimensional expansions and renormalization group calculations, Monte Carlo simulations, and phenomenological and thermodynamic analysis of concrete experimental observations.  Recent researches have focused on ionic fluids and their criticality and, in a new direction, on the biophysics of motility and the mechanochemistry of molecular motors.