Hendrik Pieter Nicolaas Muller (2 April 1859 – 11 August 1941) was a Dutch entrepreneur, diplomat, and publicist who started his career as a businessman, trading with East and West Africa.

Over the course of his life he published well over two hundred articles, brochures, and books about his travels, South Africa and the Boers, and Dutch foreign policy.

Muller's maternal grandfather, Abram van Rijckevorsel [nl], was the doyen of the Rotterdam merchant community in the early part of the nineteenth century.

Both his father and maternal grandfather were politicians as well, liberals who staunchly defended the principle of free trade, and both were at one time members of the Senate of the States-General of the Netherlands.

The Muller family was fairly prominent in the Netherlands in the nineteenth and early twentieth century, with Christian ministers, professors of literature and history, archivists, antiquarian booksellers, statesmen and businessmen in their midst.

He first attended the private institution Delfos followed by the Hogere Burgerschool (high school) in Rotterdam, before continuing his education in Germany, at the Hohe Real Schule in Frankfurt-am-Main, to specialise in trade and business.

In 1882, Muller travelled to East Africa and visited all the trading posts and establishments of the firm, changing business practices.

At the end of his trip he made an extensive tour of South Africa, visiting Natal, Zululand, Transvaal, the Orange Free State, and the Cape Colony.

After a third business journey to Africa in 1890, now to Liberia and the Gold Coast, for Hendrik Muller & Co., he returned home seriously ill, and had to convalesce for months.

His predecessor Hamelberg had not only been consul general, but had on occasion also acted as special envoy to be able to negotiate treaties and accords with foreign powers.

He also strengthened the consular representation of the Orange Free State in Europe and inquired into all kinds of practical issues like a cure for rinderpest and improved methods of irrigation.

He also renewed his relations with other leading statesmen, like former President Francis William Reitz, government secretary Pieter Jeremias Blignaut, and chairman of the Volksraad, Cornelius Hermanus Wessels.

Once back in the Netherlands, the political situation in South Africa became tense very rapidly, and Muller did all he could to propagate the cause of the Boer Republics in the press and via diplomatic channels.

Through his many contacts with the European press Muller saw to it that the Boer cause was extensively covered in the newspapers, usually in his own words, but published in the name of the respective editor.

His office in The Hague was the hub of diplomatic and consular activity in this period, with several secretaries working continuously on the gathering of information and dealing with correspondence.

The first time problems arose in the open was in 1900, when the Boer republics sent a joint Special Diplomatic Delegation to Europe and the United States, which was ill-prepared and for which Leyds had very different ideas than Muller.

In 1901, Muller travelled to the United States himself to mobilise support from President Theodore Roosevelt, especially on behalf of the women and children in the British concentration camps.

He visited British India and Ceylon, Burma, Malaysia and the Philippines and French Indochina, travelled extensively through the Dutch East Indies, and returned via Japan, Korea – where he had an audience with the last Korean emperor[3] –, Manchuria, China, and Siberia.

At the end of World War I the Dutch prime minister did acknowledge the high quality of Muller's work in setting up the camps and bringing and maintaining order and human dignity under very trying circumstances.

In this vein, in 1919, he published an article on the history and geography of Spitsbergen and the necessity for the Dutch government to defend its historic claims on the islands.

In that year the Dutch government appointed him Envoy Extraordinary and Minister Plenipotentiary to Romania, a country in the throes of political and economic transformation.

In line with his historical interests he initiated the erection of a statue for the murdered Grand Pensionary of Holland, Johan de Witt (1625–1672).

On the side of the socle a text is engraved which – in translation – reads: 'Leader and servant of the Republic, designer of it most powerful fleets, defender of the freedom of the seas, caretaker of the State's coffers, mathematician.

In the last years of his life he was honoured in several ways, among others with an honorary doctorate in law from the University of South Africa, a bust in the hall of the Eeufeesgebou of the University of the Free State, with a copy in the Rijksmuseum voor Volkenkunde (National Museum of Ethnology) in Leiden, and an honorary diner party by the Royal Geographical Society in London.

Among the attendants were several former government ministers and high-ranking military officers, university professors, former diplomats, representatives of cultural and scientific organisations, and friends from his South African period and after.

Many of the (propaganda) articles he wrote about the South African War when he was consul general for the Orange Free State were published secretly, often under another journalist's or newspaper editor's name, to maximise the public relations effect.