Dauphin of France in the context of "Battle of Patay"

An heir apparent is a person who is first in the order of succession and cannot be displaced from inheriting by the birth of another person. A person who is first in the current order of succession but could be displaced by the birth of a more eligible heir is known as an heir presumptive.

Today these terms most commonly describe heirs to hereditary titles (e.g. titles of nobility) or offices, especially when only inheritable by a single person. Most monarchies refer to the heir apparent of their thrones with the descriptive term of crown prince or crown princess, but they may also be accorded with a more specific substantive title: such as Prince of Orange in the Netherlands, Duke of Brabant in Belgium, Prince of Asturias in Spain (also granted to heirs presumptive), or the Prince of Wales in England and Wales; former titles include Dauphin in the Kingdom of France, and Tsesarevich in Imperial Russia.

Louis XVI (Louis-Auguste; French: [lwi sɛːz]; 23 August 1754 – 21 January 1793) was the last king of France before the fall of the monarchy during the French Revolution. The son of Louis, Dauphin of France (son and heir-apparent of King Louis XV), and Maria Josepha of Saxony, Louis became the new Dauphin when his father died in 1765. In 1770, he married Marie Antoinette. He became King of France and Navarre on his grandfather's death on 10 May 1774, and reigned until the abolition of the monarchy on 21 September 1792. From 1791 onwards, he used the style of king of the French.

The first part of Louis XVI's reign was marked by attempts to reform the French government in accordance with Enlightenment ideas. These included efforts to increase tolerance toward non-Catholics as well as abolishing the death penalty for deserters. The French nobility reacted to the proposed reforms with hostility, and successfully opposed their implementation. Louis implemented deregulation of the grain market, advocated by his economic liberal minister Turgot, but it resulted in an increase in bread prices. In periods of bad harvests, it led to food scarcity which, during a particularly bad harvest in 1775, prompted the masses to revolt. From 1776, Louis XVI actively supported the North American colonists, who were seeking their independence from Great Britain, which was realised in the Treaty of Paris (1783). The ensuing debt and financial crisis contributed to the unpopularity of the ancien régime.

Mary, Queen of Scots (8 December 1542 – 8 February 1587), also known as Mary Stuart or Mary I of Scotland, was Queen of Scotland from 14 December 1542 until her forced abdication on 24 July 1567.

The only surviving legitimate child of James V of Scotland, Mary was six days old when her father died and she inherited the throne. During her childhood, Scotland was governed by regents, first by the heir to the throne, James Hamilton, Earl of Arran, and then by her mother, Mary of Guise. In 1548, she was betrothed to Francis, the Dauphin of France, and was sent to be brought up in France, where she would be safe from invading English forces during the Rough Wooing. Mary married Francis in 1558, becoming queen consort of France from his accession in 1559 until his death in December 1560. Widowed, Mary returned to Scotland in August 1561. The tense religious and political climate following the Scottish Reformation that Mary encountered on her return to Scotland was further agitated by prominent Scots such as John Knox, who openly questioned whether her subjects had a duty to obey her. The early years of her personal rule were marked by pragmatism, tolerance, and moderation. She issued a proclamation accepting the religious settlement in Scotland as she had found it upon her return, retained advisers such as James Stewart, Earl of Moray (her illegitimate half-brother), and William Maitland of Lethington, and governed as the Catholic monarch of a Protestant kingdom.

Marie Antoinette (/ˌæntwəˈnɛt, ˌɒ̃t-/; French: [maʁi ɑ̃twanɛt] ; Maria Antonia Josefa Johanna; 2 November 1755 – 16 October 1793) was the last queen of France before the fall of the monarchy during the French Revolution. She was the wife of King Louis XVI.

Born an archduchess of Austria, she was the penultimate child and youngest daughter of Empress Maria Theresa and Emperor Francis I of the Holy Roman Empire. She married Louis Auguste, Dauphin of France, in May 1770 at age 14, becoming the Dauphine of France. On 10 May 1774, her husband ascended the throne as king, and she became queen.

Henry II (French: Henri II; 31 March 1519 – 10 July 1559) was King of France from 1547 until his death in 1559. The second son of Francis I and Claude, Duchess of Brittany, he became Dauphin of France upon the death of his elder brother Francis in 1536.

As a child, Henry and his elder brother spent over four years in captivity in Spain as hostages in exchange for their father. Henry pursued his father's policies in matters of art, war, and religion. He persevered in the Italian Wars against the Habsburgs and tried to suppress the Reformation, even as the Huguenot numbers were increasing drastically in France during his reign.

Catherine de' Medici (Italian: Caterina de' Medici, pronounced [kateˈriːna de ˈmɛːditʃi]; French: Catherine de Médicis, pronounced [katʁin də medisis]; 13 April 1519 – 5 January 1589) was an Italian Florentine noblewoman of the Medici family and Queen of France from 1547 to 1559 by marriage to King Henry II. She was the mother of French kings Francis II, Charles IX, and Henry III, and a cousin to Pope Clement VII. The years during which her sons reigned have been called "the age of Catherine de' Medici" since she had extensive, albeit at times varying, influence on the political life of France.

Catherine was born in Florence to Lorenzo de' Medici, Duke of Urbino, and his wife, Madeleine de La Tour d'Auvergne. In 1533, at the age of 14, Catherine married Henry, the second son of King Francis I and Queen Claude of France, who would become Dauphin of France (heir to the throne) upon the death of his elder brother Francis in 1536. Catherine's marriage was arranged by Clement VII. Henry largely excluded Catherine from state affairs during his reign, instead showering favours on his chief mistress, Diane de Poitiers, who wielded significant influence in the court. Henry's sudden accidental death in 1559 thrust Catherine into the political arena as mother of the frail 15-year-old Francis II. When Francis II died the next year, she became regent on behalf of her 10-year-old son Charles IX and thus gained sweeping powers. After Charles died in 1574, Catherine played a key role in the reign of her third son, Henry III. He dispensed with her advice only in the last months of her life but outlived her by just seven months.

Louis, Dauphin of France, Duke of Burgundy (16 August 1682 – 18 February 1712), was the eldest son of Louis, Grand Dauphin, and Maria Anna Victoria of Bavaria and grandson of the reigning French king, Louis XIV. He is commonly known as le Petit Dauphin to distinguish him from his father. When his father died in April 1711, the Duke of Burgundy became the official Dauphin of France. Described by his contemporaries as a pious, intellectual, gentle and shy man who was faithful and loving to his wife, he never reigned, as he died in 1712 while his grandfather was still on the throne. Upon the death of Louis XIV in 1715, the Duke of Burgundy's third son became Louis XV.

A crown prince or hereditary prince is the heir apparent to the throne in a royal or imperial monarchy. The female form of the title, crown princess, is held by a woman who is heir apparent or is married to the heir apparent.

Crown prince as a descriptive term has been used throughout history for the prince who is first-in-line to a throne and is expected to succeed (i.e. the heir apparent), barring any unforeseen future event preventing this. In certain monarchies, a more specific substantive title may be accorded and become associated with the position of heir apparent (e.g. Prince of Wales in the United Kingdom, Prince of Asturias in the Kingdom of Spain and formerly the Dauphin in France). In these monarchies, the term crown prince may be used less often than the substantive title (or never).