Blanche Zélia Joséphine Delacroix, better known as Caroline Lacroix (French pronunciation: [kaʁɔlin lakʁwa]; 13 May 1883 – 12 February 1948), was the most prominent and notorious of Leopold II of Belgium's mistresses.

Because of these presents, Caroline was deeply unpopular both among the Belgian people and internationally, as Leopold became increasingly criticized for his greed-induced actions in the Congo Free State, his own personal colony.

After the king's death, it was soon discovered that he had left Caroline numerous properties, items of high material value, Congolese bonds, and other valuable sources of income – all of which turned her into a multimillionaire.

[1] According to Adam Hochschild, Durrieux liked to support the two of them by betting on horse races; when his luck soured, he became a form of pimp, prostituting Caroline to well-born clients.

[1] As Leopold II was unknown to her, Caroline was so flustered with the encounter that she mixed up Belgium and Sweden in the king's presence, referring to him as His Majesty Oscar, to his surprise and amusement.

[3] The two aides' purpose soon became clear: one sat on each side of her and began asking questions that required her to "turn my head first to the right, then to the left ... their only aim, as I learned later, being to show off my two profiles to the mute personage", according to her memoirs.

[6] Her habit of accompanying Leopold to fashionable spas in Europe provoked further disbelief and outrage, with some speculating that she perversely pleasured the old king with the use of strategically placed mirrors and "special" equipment.

Caroline tried to pass him off as her brother when Leopold caught the two together; one publication reported that she and Durrieux had placed secret electric bells in all her residences so that servants could warn her when the king was approaching.

[12] As the years went by and the king became increasingly prone to outbursts of anger, breaking with all his old relationships, it was said that only in Caroline and their sons' company did Leopold "recapture some of his vitality and Germanic humour".

[14] Caroline was described as having been above average in height, "plump but graceful, with a beautiful complexion and skin", with masses of chestnut hair; in character, she was "haughty, sharp, irritable" and ill-educated, and insisted on being treated with respect or else one would have to face the king's displeasure.

[18] The marriage caused a great scandal in Belgium, as its citizens were shocked that the Church had not only sanctioned it, but also allowed Caroline to remain at his bedside, even when the priest was present.

[16] Leopold died in the presence of Caroline and two nurses; his youngest legitimate child Princess Clémentine, who had been barred from entering his palace before, was still not allowed to go into his room despite his weakening condition.

[9] Had Leopold married in a legal civil ceremony, the boy could have indeed inherited the throne, because all classes were equal under the Belgian constitution, and thus their marriage would not have been considered morganatic.

[23] However, this applied only in Belgium and not abroad; consequently, much of the wealth he distributed for safekeeping was in foreign investments or in the shape of paintings, bric-a-brac, and art treasures that could be easily converted into cash.

[19] Princess Louise soon went after these securities, but with the help of men loyal to the king, Caroline was able to safely spirit away the majority of her wealth to Paris; two of her estates (in Brussels and in France) were boarded up however, disallowing her from entering them.

[27] The old king's estrangement from his three daughters from his first marriage (Princesses Louise, Stéphanie, and Clémentine) spurred Leopold to keep or give as much wealth away as possible in order to disinherit the girls.

[30] Belgian statesman Emile Vandervelde later charged in an open letter that Leopold had given Caroline $6,000,000 worth of Congo bonds which had been found to be previously missing when Belgium annexed the colony.

[29] He was formerly a non-commissioned officer in the French army, and served as her chief agent at the time of Leopold's death, helping her collect the necessary papers to secure her inherited fortune.

[17] Because of Durrieux's earlier role in prostituting Caroline off for money, Adam Hochschild speculates that if she had shared some of her riches with him, their arrangement was "surely one of the most successful feats of pimpery of all time".

[17][29] Caroline and her second husband divorced soon after, and she was able to keep the bulk of her wealth intact (though she settled on Durrieux a sum of one million dollars in order to retain custody of her two sons).