Arc modular light devices, systems, and methods. In at least one exemplary embodiment of a module system of the present disclosure, the module system comprises a plurality of LED modules, each LED module comprising an outer housing, a light source positioned within the outer housing, and a lens positioned so that light from the light source can be emitted through the lens; and a plate configured to couple to each of the plurality of LED modules; wherein the module system is configured to focus light from the LED modules inward when the plate has a concave curvature; and wherein the module system is configured to spread light from the LED modules outward when the plate has a convex curvature.