he wasn't simply a power-mad tyrant like Ivan the Terrible, or a desperate defender of his realm like Vlad the Impaler.
No, he was simply driven by greed and cruelty satisfying that greed.
Imagine Jim Fisk as a king:
Leopold was the founder and sole owner of the Congo Free State, a private project undertaken on his own behalf. He used Henry Morton Stanley to help him lay claim to the Congo, the present-day Democratic Republic of the Congo. At the Berlin Conference of 18841885, the colonial nations of Europe authorized his claim by committing the Congo Free State to improving the lives of the native inhabitants. From the beginning, Leopold essentially ignored these conditions. He ran the Congo using the mercenary Force Publique for his personal enrichment. He used great sums of the money from this exploitation for public and private construction projects in Belgium during this period. He donated the private buildings to the state before his death, to preserve them for Belgium.
Leopold extracted a fortune from the Congo, initially by the collection of ivory, and after a rise in the price of rubber in the 1890s, by forced labour from the native population to harvest and process rubber. Leopold's regime was characterized by notorious systematic brutality; men, women and children had hands amputated for failing to deliver their quota of rubber; thousands were sold into slavery. These and other facts were established at the time by eyewitness testimony to and on-site inspection by an international Commission of Inquiry (1904). Millions of the Congolese people died: modern estimates range from one million to 15 million deaths, with a consensus growing around 10 million. Several historians argue against this figure due to the absence of reliable censuses, the enormous mortality of diseases such as smallpox or sleeping sickness, and the fact that there were only 175 administrative agents in charge of rubber exploitation.[2][3]
Reports of deaths and abuse induced the Belgian government to develop a civil administration, free from Leopold's oversight, for the Congo in 1908.
Belgium was not trying to be a world power, so was largely ignored.
His sins being in Africa, not Europe or North America, is likely the main reason they are not so well known.