In darwinism, the interactor is the part of the organism, selection acts on. In biological systems, this is the phenotype, the outward traits most affected by natural selection.

a reference to an object, with a

(Amulet) In a GUI presentation, interactors are invisible objects that attach to graphical objects in order to allow them to respond to input.

a self-contained autonomous agent which has an expertise of data processing and user interaction

an entity that interacts directly with its environment