This chapter outlines working definitions of the genres Crime and True Crime. This includes details of their constituent parts, and the ways in which their conventions—or lack thereof, in the case of the latter—have been adhered to and deviated from across historic periods. Their points of commonalities and differences are outlined, to consider the ways in which Crime fiction has become a genre at once recognisable owing to its landmark authors and set formulas. Meanwhile, True Crime is a genre more recognisable owing to its graphology and its current cultural significance and status, rather than set writing formulas or structures, or indeed, time-honoured authors. In accompaniment to this, Crime fiction’s so-called Golden Era is highlighted as a vehicle through which the genre has become more established and respected. While in contrast, True Crime lacks such distinct eras in its history; regardless of its age, cited here as being centuries old. An argument is made that while some may consider the current climate to be True Crime’s Golden Era, ultimately this line of thought lacks nuance, without greater consideration being given to the time periods and influential authors that came decades earlier.