Greece obtained independence from the Ottoman Empire in 1829, with considerable help from the Great Powers of Britain, France, and Russia, initially as a republic, but later renegotiated to be a monarchy. The first candidate for a Greek monarch was from the House of Saxe-Coburg and -Gotha, the future Leopold I of Belgium, but he wasn't happy with the borders of Greece, which were considerably smaller than the borders today, and the historic borders of what might be considered Greece.

The second candidate was Otto, of the Bavarian House of Wittelsbach, who accepted the offer and was approved by the Greek National Assembly. His thirty-year reign was however very unpopular, as he was unable to deal with Greece's poverty, refused many requests for a constitution before giving to an insurrection of both the people and the army, and was generally seen as controlled by and representing the Great Powers, allowing them to walk all over Greece. Ultimately, he was a weak, inexperienced, and unpopular ruler. His biggest embarrassment was attempting to expand the Greek border northward during the Crimean War, which ended in Greece being blockaded and practically invaded by the Great Powers on which Otto depended.

Left without support abroad or at home, Otto was, in the end, deposed and forced back to Bavaria, with the Greeks holding a referendum to determine their next monarch. The British Prince Alfred received the overwhelming majority of the vote, but due to the conditions of Greek independence laid out in 1832, he was unable to accept the position. Russian and French monarchs and princes were runner-up candidates, but they had the same constraints. In addition to this, a handful of other candidates refused due to the difficult conditions left in Greece by Otto and their obvious unpopularity compared to Prince Alfred.

In the negotiations that followed between the Great Powers and with Greece, the only candidate agreeable to all sides was Prince William of Denmark (edit: he adopted the name George upon being proclaimed King). In the end, he proved quite popular; being able to speak Greek, expanding the borders northward, supporting a new constitution, and frequently touring Greece. From there, it is a simple matter of succession to the other kings of Greece/Kings of the Hellenes.