South Africa
A country aptly named for its location – at the southern tip of the African continent. It has a place on dark tourism's map for its very own dark chapter in 20th century history: the grim years of Apartheid, which also left the country largely isolated from much of the rest of the world. But it is also a country that successfully managed to overcome that dark chapter – and a couple of sites related to the years of repression during Apartheid are now open to (dark) tourists.
All in all, however, there isn’t that much for the dark tourist to see, and mostly in in Johannesburg and in or around Cape Town, but esp. Robben Island is a must – in fact it is one of the most impressive dark tourism sites in the world (see top 20).
While most of the dark attractions in South Africa are related to apartheid and the struggle to overcome it, I was quite surprised to also find a Holocaust museum in Cape Town when I was there in 2003 ... because of the fact that the country itself was hardly affected by it, being located so far away from Europe! Meanwhile two more branches of this Holocaust Centre have opened, one in Johannesburg, the other in Durban.
Also in Johannesburg there are Apartheid-themed guided tours of the (in)famous township of Soweto and the city also has a couple of museums related to different aspects of the topic. I went to see those when I had two stop-overs in Jo'burg en route to St Helena and Zimbabwe in July/August 2018.
South Africa's main tourism industry is of course anything but focused on the dark. It's its nature and wildlife that trump everything. The north-east of the country offers some of the best safari territories in the world, and not just in the world famous Kruger Park.
The private game reserves adjacent to Kruger are even better, as they offer much more intimate animal encounters. On my first morning safari in the Sabi-Sabi reserve I got so close to a leopard I could almost have touched it from the jeep (of course I didn't attempt actually doing so), as our ranger and tracker were going off-road. You don't get that in Kruger Park! And this was followed by superb encounters with all manner of other fantastic animals, not just the "Big 5" that everybody is conventionally after. But also even more interesting and rarer animals such as the wonderful African wild dog. I stayed at Sabi-Sabi's Selati lodge, which was fantastic (e.g. for it being so small, intimate and: unfenced! – but esp. for the wonderful staff). But I understand that there are many other lodges offering similarly superb experiences. Shop around – but don't be too miserly. Staying at such private game reserve lodges can be very expensive, but what you get in additional experience compared to more budget options such as in or around Kruger Park is worth every extra penny.
There are also great opportunities for wildlife watching in other parts of the country, including whale watching from the coast (especially at Hermanus). A somewhat "dark" attraction of marine wildlife watching is cage-diving with sharks! That is: you go down into the water protected by a cage while around you sharks are proffered food so that you can watch them close up – but in safety – yet the thrill of being so close to those powerful white sharks is part of the package, of course.
Wildlife aside, there's also just lots of plain beautiful scenery all round too, e.g. the Drakensberg and the southern end of the Great African Rift Valley in general. Or the magnificent Blyde River Canyon … to name just a few.
Last but not least it's also a great country in culinary terms (see food and drink). The various ethnic influences and rich resources make for an incredibly diverse and magnificently flavoursome cuisine, which I would rank as one of the best in the world. And let's not forget the country's excellent wines! And such delights are remarkably affordable too, for the levels of quality you can get. Carnivores can also sample the delights of exotic meats they probably won't get anywhere else, but for me it was the seafood, esp. done in the Cape Malay style. The curry flavourings of that style blew me away. Magnificent.
However, the country has a bit of a security issue. The divide between rich and poor is gaping and that has consequences which the abolition of Apartheid could not resolve. As a black taxi driver told me en route from Cape Town airport: "it's no longer the colour of one's skin that makes or breaks people, it's the colour of one's money". The well-heeled tend to live in high-security fortresses. And for a reason. Violent burglaries are far from uncommon. Street crime in certain areas is no less a problem. Carjackings are an issue (hire cars are targeted too).
All this means that the country isn't the best for independent travel, for safety reasons alone, in particular not for lone travellers! Therefore it's more advisable to do something organized, with drivers where required. It doesn't cost the world, and it doesn’t have to mean travelling in large groups. Itineraries can be tailored to suit every taste, including very private or small-group arrangements. So don't let the security issue hold you back – just use your common sense and don't take unnecessary risks.