Dark tourism has attracted increasing academic attention, but the extent to which it exists as a separate form of tourism from heritage tourism is not yet clear. Despite the growth of UNESCO World Heritage Site designations, little research has considered the relationship between dark tourism and World Heritage Sites. Because the development of dark tourism is beset with ethical concerns, heritage professionals can have negative perceptions about the acceptability or attractiveness of it for the sites that they are involved in managing. This research used a qualitative Delphi Panel method to evaluate stakeholder perceptions of the potential development of dark tourism to the Greenwich Maritime World Heritage Site in London, United Kingdom. The findings show that stakeholders are broadly supportive of tourism to the site and positive about future tourism growth. Despite this, they did not support the development of dark tourism to the site because it was perceived as inauthentic, tacky and sensationalist. In order to address this issue, recommendations are made that future attempts to develop dark tourism at WHS should involve enhancing the knowledge of stakeholders about dark tourism, and of the resources within their sites that could be included in a dark tourism offer to tourists.