The article is an attempt at applying the concept of counterfactuality, typically employed with reference to narrative forms, to the analysis of visual culture, particularly to theatre photography. The material for case studies is provided by the works of Polish photographers who redefine the function of this form of photography. Typically, photography is seen by theatre historians as the prime form of theatre documentation, and therefore treated as subservient to the needs of theatre studies as an academic discipline. Contrary to that, the photographic projects analysed in the present paper (particularly those of Ryszard Kornecki and Magda Hueckel), although made in theatre during performances, have been produced and distributed as autonomous art forms which neither represent nor document theatre productions. In the analysis of these projects, I employ Margaret Olin’s concept of “performative index”, which describes the relationship between the image and the viewer as a dynamic creation of meaning. With reference to this theoretical framework, I argue that counterfactuality of theatre photography is a strategy of turning this medium into an autonomous form of art.