Frederick VII (Frederik Carl Christian) (6 October 1808 – 15 November 1863) was King of Denmark. He reigned from 1848 until his death. He was the last Danish monarch of the older Royal branch of the House of Oldenburg, and also the last king of Denmark to rule as an absolute monarch. During his rule, he signed a constitution that gave Denmark a parliament and made the country a constitutional monarchy.

Frederick VII managed to make himself one of the most beloved of the Danish Kings of recent times. This was probably due to his giving up absolutism but also to his personality. In spite of many weaknesses confirmed by his contemporaries — drinking, eccentric behavior, etc. — he also possessed something of a gift as an actor. He could be both folksy and genuinely hearty, being able to appear as a ”simple, yet dignified monarch”. During his many travels throughout Denmark he cultivated his contacts with the common man. He was also a keen antiquarian and according to the later Danish archaeologist P.V. Glob, it was "he, more than anyone else, [who] helped to arouse the wide interest in Danish antiquities". His motto was: The people's love, my strength.

Frederick was born at Amalienborg Palace to Christian VIII of Denmark and Duchess Charlotte Frederica of Mecklenburg-Schwerin. His maternal grandparents were Friedrich Franz I, Grand Duke of Mecklenburg-Schwerin and Luise, Duchess of Saxe-Gotha.

The king's first two marriages both ended in scandals and divorces. He was first married in Copenhagen on 1 November 1828, separated in 1834 and divorced in 1837 to his second cousin, Princess Vilhelmine Marie of Denmark, a daughter of Frederick VI, and remarried on 10 June 1841, to Caroline Charlotte Mariane of Mecklenburg-Strelitz (Neustrelitz, 10 January 1821 – Neustrelitz, 1 June 1876), whom he divorced in 1846. In Frederiksborg on 7 August 1850 he morganatically remarried to Lovisa Christina Rasmussen (Copenhagen, 21 April 1815 – Cannes or Genoa, 6 March 1874), created lensgrevinde Danner in 1850 (in Denmark famous as Countess Danner), a common milliner and former ballet dancer who had for many years been his acquaintance or mistress, natural daughter of G.L. Köppen and of Juliane Caroline Rasmussen. This marriage seems to have been happy although it aroused great social indignation among the nobility and the bourgeoisie. Countess Danner, who was denounced a vulgar gold-digger by her enemies, but a doughty and unaffected “daughter of the people” by her admirers, seems to have had a stabilizing effect on him. She also worked at maintaining his popularity by letting him “meet the people” of the provinces.

The expectation that Frederick would not likely produce an offspring, despite numerous affairs, was widespread, but sources rarely state the reasons. Some speculate that Frederick was merely infertile. Already during the reign of Frederick's father, King Christian VIII, the succession question was brought forward. It has recently been claimed that the king did indeed father a son, Frederik Carl Christian Poulsen, born on 21 November 1843, as a result of his relation to Else Maria Guldborg Pedersen (also referred to as Marie Poulsen) which took place after his first two unhappy marriages. This was brought forward in a book published in 1994 and again in a book published in 2009. According to an article in Politiken, the author of the latter book, who believes herself to be the great-granddaughter of Frederick VII, is in possession of four letters from the King to Marie Poulsen in which he acknowledged paternity. The letters are quoted in the book. In all cases, however, extramarital offspring were and still are barred from the line of succession.

It has been claimed Frederick had a same-sex relation to his friend Carl Berling, printer and owner of the newspaper Berlingske Tidende. The bisexual Berling had an illegitimate child with Louise Rasmussen, Carl Christian, who was much liked by the King, to the extent that he insisted on signing the new constitution on Carl Christian's 8th birthday on 5 June 1849. To retain a tinge of decency, the King married Louise Rasmussen and the trio then moved into the royal castle where Berling was appointed Chamberlain and remained till 1861. The public indignation within higher circles over Frederick's morganatic marriage is well-known, but reasons have rarely been explained in detail.

Frederick who was the last king of the older branch of the Oldenburg dynasty had a rather neglected childhood after the divorce of his parents. His youth was marked by private scandals and for many years he appeared as the ”problem child” of the royal family.

When he succeeded to the throne January 1848 he was almost at once met by the demand for a constitution. Besides the Schleswig-Holsteiners wanted an independent state while the Danes wished to maintain South Jutland as a Danish area. The king soon yielded to the Danish demands, and in March he accepted the end of absolutism, which resulted in the first June Constitution of 1849. During the First War of Schleswig against the German powers in 1848 – 51 Frederick appeared as ”the national leader” and was regarded almost as a war hero despite having never taken any active part in the struggles.

During his reign Frederick as a whole behaved as a constitutional monarch. However he did not quite give up interfering in politics. In 1854 he contributed to the fall of the strongly conservative Ørsted Cabinet and in 1859 – 60 he accepted a liberal government which was appointed on the initiative of his wife. During the crisis in the Duchies 1862 – 63 shortly before his death he also openly spoke for an inter-Scandinavian military co-operation. Those minor crises created frictions and maintained some permanent insecurity but it did not damage his general popularity. In some of these affairs he overstepped the mark beyond any doubt; on the other hand the first Danish constitution was somewhat vague as regards to the limits of royal power.

The rule of Frederick was also the golden age of the National Liberal Party which was in office from 1854. This period was marked by some political and economic reforms, such as beginning the demolition of the walls around Copenhagen and the introduction of free trade in 1857. The constant quarrels with the opposition regarding the Schleswig-Holstein Question and the German demands of not trying to unite Denmark with Schleswig (South Jutland) led to some changes to the constitution in order to fit the foreign political situation which created frustration in Denmark. The National Liberals therefore at last favored a more resistant course against the Germans which led to the Second War of Schleswig in 1864. The king wholeheartedly supported this course and just before his sudden death he was prepared to sign a new special constitution for Denmark and Schleswig (the so-called November Constitution).

Frederick VII was the 978th Knight of the Order of the Golden Fleece in Spain in 1848.

Frederick was married three times, and had numerous affairs to boot, but produced no issue. The fact that he reached middle age without producing an heir meant that Prince Christian of Glücksburg (1818 – 1906), the descendant of a cousin of King Frederick VI, was chosen to succeed him in 1852. When Frederick died in 1863, Christian took the throne as Christian IX.

Because of Salic law, the succession after childless Frederick was a difficult question to arrange, and it did not go smoothly, but caused a war. Nationalism in the German speaking parts of Schleswig-Holstein meant that no solution to keep the Duchies united with Denmark was satisfactory. The duchies were inherited according to the salic law among descendants of Helwig of Schauenburg, the senior of which after Frederick himself was Frederick, Duke of Augustenburg (who proclaimed himself Duke of Schleswig-Holstein after Frederick VII's death). This Friedrich von Augustenburg had become the symbol of the nationalist German independence movement in Schleswig-Holstein, since the time that his father, in exchange for money, had renounced his claims as first in line to inherit the twin Duchies of Schleswig and Holstein, following the London Protocol of 8 May 1852, which concluded the First War of Schleswig. Because of his father's renunciation, Frederick was regarded as ineligible to succeed.

Denmark was also under Salic Law, but only among descendants of Frederick III (who was the first hereditary monarch of Denmark, since before him the Kingdom had been officially elective). Therefore, the members of the Schleswig-Holstein branches of Augustenborg and Glücksburg, agnates with the King, were not allowed to succeed under that provision. Agnatic descendance of Frederick III went extinct when Frederick VII died, and at that point, the succession law promulgated by Frederick III provided a "semi-Salic" succession. There were however several alternative ways to interpret the line of succession, because the provision was not entirely clear on whether it be the closest female relative or what to inherit. The question was solved by an election and a separate law to confirm the new successor.

The closest female relatives of Frederick VII were the issue of his paternal aunt, Louise, who had married a cadet Landgrave of Hesse. However, they were not agnatic descendants of the Royal Family and thus not eligible to succeed in Schleswig-Holstein. The dynastic female heiress according to the original primogeniture from Frederick III were the childless daughters of the late king Frederick VI, after whom the original primogeniture would have led to heirs of Louise, sister of Frederick VI, who had married the then-Duke of Augustenburg. The chief heir to that line was the selfsame Frederick of Augustenburg, but his turn would have come only after the death of a childless Princess who was very much alive in 1863.

Some rights belonged also to the Glücksburg line, a more junior branch of the Royal clan. They were also heirs of Frederick III, through their one ancestress who was a daughter of King Frederick V of Denmark, and they were more junior agnatic heirs eligible to succeed in Schleswig- Holstein. They were Christian of Glücksburg (1818 – 1906) and his two elder brothers, eldest of whom was childless, but the second had produced children, also male children.

Prince Christian of Glücksburg (1818 – 1906) had been a foster "grandson" of the sonless royal couple Frederick VI and Queen Marie Sophie, thus familiar with the Royal Court and the traditions of the recent monarchs. Prince Christian was great-nephew of Queen Marie Sophie, and descendant of a first cousin of Frederick VI. He was brought up as Danish, having lived in Danish speaking lands of the Royal Dynasty, and was not attached to German nationalism. Although these did not mean anything legally, they made him a relatively good candidate from the Danish viewpoint. As a junior agnatic descendant, he was eligible to inherit Schleswig-Holstein, but not the first - in - line. As descendant of Frederick III, he was eligible to succeed in Denmark, but not first - in - line, however that line was not very clear.

Christian of Glücksburg (1818 – 1906) married Princess Louise of Hesse, eldest daughter of the closest female relative of Frederick VII. Louise's mother and brothers, Princes of Hesse, renounced their rights in favor of Louise and her husband. Prince Christian's wife was now the closest female heiress of Frederick VII.

The thorny question of operation of semi-Salic provision in succession of Denmark was at that point resolved by legislation through which Prince Christian of Glücksburg (1818 – 1906) was chosen in 1852 to succeed King Frederick VII in Denmark.

Frederick VII died in Glücksburg in 1863 and was interred in Roskilde Cathedral. Christian took the throne as Christian IX.

In November 1863, Frederick of Augustenborg claimed the twin-duchies in succession after King Frederick VII of Denmark, who also was the Duke of Schleswig and Holstein and who had died without a male heir.

Prussia and Austria started the Second War of Schleswig.