In his account of captivity in Morocco in the 1680s, Thomas Phelps recalled meeting with an “ancient Moor, who formerly had been a slave in England and spoke good English, and who was set at liberty by our late Gracious King Charles the 2d.” Another captive/slave was the corsair Abdallah bin Aisha, who spent three years in England and was released by King Charles without ransom upon the intercession of James II.”
Source: Turks, Moors, and Englishmen in the Age of Discovery Nabil Matar
“Moors have been present in Europe from classical times. In the 2nd and 3rd centuries Roman soldiers of [African] origin served in Britain, and some stayed after their military service ended.”
Source: Black Moors in Scotland.
The Restoration of the monarchy began in 1660 when the English, Scottish and Irish monarchies were all restored under King Charles II, “the Moor” after the republic that followed the Wars of the Three Kingdoms. There are several historical references referring to Charles II as having a “Black Complexion” or as a “Black Boy“. “It was a nickname for him (coined by his mother) because of the darkness of his skin and eyes.”
Source: 10 Things You Didn’t Know About Charles II and his Reign.
“Pubs across England called The Black Boy are generally named after Charles“. “Since the early 16th Century, The Black Boy Inn hotel in Caernarfon has been welcoming weary travelers and visitors to the Town of Caernarfon and region of Snowdonia.” Source: Black Boy Inn
According to Black Boys Inn B&B in Berkshire
“The word “Stuart” comes from the old nordish root Svart which means “black”. Stuart is the same word as Swarthy, which means black in old English. There was once a Stuart line of Kings in England. The name of the founding ancestor was Stuart which means Black man. Stuart Kings of England and Scotland, King Charles II, also lovingly known as the “black boy” of England by his subjects. He is commemorated in the celebrated name of the Black Boy Inn, found all over the British Isle. King Charles II was a black man.”
Source: Welcome to The Black Boys Inn B&B in Berkshire
At this time we disagree with Black Boys Inn B&B in Berkshire that “Stuart” comes from the old nordish “Svart“. “Svart” is the root of “Swarthy” and Charles II is described as having a “Swarthy Complexion” and alternatively a “Black Complexion“. Thus, we do not need “Stuart” to derive from “Svart” in order to authenticate the descriptions that Charles II’s complexion was “Black“.
“Stuart is the French form of the Scottish surname Stewart. The French form of the name was brought to Scotland from France by Mary Stuart, in the 16th century.”
Source: Hanks, Patrick; Hodges, Flavia (2006). Hardcastle, Kate (ed.). Oxford Dictionary of Names (2nd ed.). Oxford: Oxford University Press. p. 253. ISBN 978-0-19-861060-1.
Stewart Name Meaning Scottish: “originally an occupational name for an administrative official of an estate, from Middle English stiward, Old English stigweard, stiweard, a compound of stig ‘house(hold)’ + weard ‘guardian’. In Old English times this title was used of an officer controlling the domestic affairs of a household, especially of the royal household; after the Conquest it was also used more widely as the native equivalent of Seneschal for the steward of a manor or manager of an estate.”
Source: Dictionary of American Family Names ©2013, Oxford University Press
“swart (adj.) Old English sweart “black, dark,” of night, clouds, also figurative, “wicked, infamous,” from Proto-Germanic *swarta- (source also of Old Frisian, Old Saxon, and Middle Dutch swart, Dutch zwart, Old Norse svartr, German schwarz, Gothic swarts “dark-colored, black“), from PIE root *swordo- “dirty, dark, black” (source of sordid). The true Germanic word, surviving in the Continental languages but displaced in English by black. Of skin color of persons from late 14c. Related: Swartest.” Source: Swart. “Swarthy” alteration of swarty, from swart + -y, from Old English sweart (“black”).” Source: Swarthy “SVART” means “Black” Source: Nordic Names

In addition to those references noted above there are others referring to his heirs as well as having a Black Complexion like Charles II. Following the references, I came upon the source of Charles II’s black complexion, which based upon the following references I believe to be inherited from his Medici ancestry. The Medici produced four Popes of the Catholic Church—Pope Leo X (1513–1521), Pope Clement VII (1523–1534), Pope Pius IV (1559-1565) and Pope Leo XI (1605)—and two queens of France—Catherine de’ Medici (1547–1589) and Marie de’ Medici (1600–1630).

In 1550 William Thomas, in his Principal rules of the Italian grammar, defined ‘Moro’ as ‘ a Moore or blacke man’, as if the two were synonymous.”
Source: Black Tudors: The Untold Story by Miranda Kaufmann
“As late as 1398 we find the following reference to the ‘Moors’: “Also the nacyn (nation) of Maurys (Moors) theyr blacke colour comyth of the inner partes.”

“Charles II of England came of this stock. G. F. Young says of the latter, “His dark hair and swarthy complexion showed traces of the Medici blood.”12* One of the Medicis, Alessandro, “The Moor,” [was] first reigning Duke of Florence. “
Source: Sex and Race: The old world J. A. Rogers Helga M. Rogers, Jun 15, 1970
“Charles Lenos, Duke of Richmond,”He is….. well shaped, Black Complexion, much like King Charles; not Thirty Years old.” (Page 36)
“Charles, Duke of St. Albans, Is Son to King Charles the Second, by Mrs. Gwyn;…. He is of a Black Complexion, not so tall as the Duke of Northumberland, yet very like King Charles. Turned of Thirty Years old.” (Page 40.)
“Alessandro’s purported mother, and indeed Alessandro himself, was sometimes referred to as a “Moor.”
Source: Was the Black Prince Black? And Other Historical Questions By John T. Scott

“He is of a black complexion, not so tall as the Duke of Northumberland [Charles’s son by the famous Lady Castle- maine],..There are also portraits, few of any artistic merit, of the fair and frail Louise do Querouailles, whom created Charles II [ portrait].”

“Charles II, King of England, who was referred to by such labels as “Black Boy” (Harvey, 1 976, 20), and as possessing “unaesthetic swarthiness “
“Charles II (1630-85), otherwise known as the Merry Monarch, was a gargantuan baby. At four months he already looked, his mother complained, like a one-year-old. From the age of 12 he took part in English civil war battles and was described as “a tall, black man” in parliamentary wanted posters. His appearance was anything but English, the dramatic height and darkness most probably inherited from Danish and Italian grandmothers. At 6ft 2in, he was almost a foot taller than his father, and he increased it with towering high heels.”
Source: Charles II: Art and Power review – the original king of bling
“Charles’ appearance was anything but English, with his sensuous curling mouth, dark complexion, black hair and dark brown eyes, he much resembled his Italian maternal grandmother, Marie de Medici’s side of the family. During his escape after the Battle of Worcester, he was referred to as ‘a tall, black man’ in parliamentary wanted posters. One of the nick-names he acquired was the black boy His height, at six feet two inches, probably inherited from his Danish paternal grandmother, Anne of Denmark, also set him apart from his contemporaries in a time when the average Englishman was far smaller than today.”
Source: Charles II 1660-85 Early Life
Louis XIV is that he was first cousin to none other than king Charles II. Lady Antonia Fraser’s book “King Charles II” provides:

“First of all, he had an abnormal darkness of complexion, a truly saturnine tint. This darkness was the subject of comment from the first. His mother wrote jokingly to her sister-in-law that she had given birth to a black baby and to a friend in France that ‘he was so dark that she was ashamed of him’. She would send his portrait ‘as soon as he is a little fairer’. But Charles never did become fairer. Later the sobriquet ‘the Black Boy’ would be used, still commemorated in English inn signs.”
“There was definitely a strain of very dark, swarthy Italian blood in the French royal family, inherited through Marie de Medici, which might and did emerge from time to time. Anne of Austria, wife of Henrietta Maria’s brother Louis XIII, was said to have given birth to a baby having the ‘colour and visage of a blackamoor‘, which died a month after its birth. In 1664 another Queen of France, wife of Charles’ first Cousin Louis, was supposed to have given birth to a black child. There was even a ‘fanatic’ fantasy at the time of the Popish Plot in the 1670s, that Charles had been fathered on Henrietta Maria by a ‘black Scotsman‘ – a neat combination of the two prejudices of the time, against the Catholics and the Scots. So it became convenient to refer to the then King as that ‘black Bastard‘.”
“Of the many grandchildren of Marie de Medici, Charles was the only one to look purely Italian; the rest being in general both frailer and paler. But his appearance was certainly a complete throwback to his Italian ancestors, the Medici Dukes of Tuscany. Directly descended as he was from Lorenzo the Magnificent there is a striking resemblance in their portraits. Bishop Burnet, alluding to Charles’ Italianate appearance and intending to make a political point concerning tyranny, comparing the King to a statue of Tiberius. Marvell was presumably describing the same phenomenon when he described Charles as Of a tall stature and of sable hue Much like the son of Kish, that lofty Jew..”
“Anne of Austria, wife of Henrietta Maria’s brother Louis XIII, was said to have given birth to a baby having the ‘colour and visage of a blackamoor’ was the mother of Louis XIV, making the baby with the ‘colour and visage of a blackamoor‘ the older brother of Louis XIV. So, to put it another way, the older brother of Louis XIV who died a month after birth had the ‘colour and visage of a blackamoor‘ . He probably isn’t called a “brother” because some cultures require a child to live to a certain age to become a “person”. The black child supposed to have been born to another Queen of France, wife of Charles’ first cousin Louis is the woman below.”
Source: King Charles II Front Cover Antonia Fraser Macdonald Futura, 1979 – Great Britain

https://www.nationalarchives.gov.uk/pathways/blackhistory/early_times/moors.htm
The Black Moors in Scotland exhibit states: King James IV (1473-1513) and the Black Moors of his Court
“James was a popular, fun-loving king with many interests. Many Black Moors were present at his court. Some worked as servants or (possibly) slaves, but others seem to have been invited guests or musicians. We know that he courted Margaret with lute and clavichord recitals and took her out hunting and playing sports.”
Source: Black Moors in Scotland
“From 1642, Charles fought the armies of the English and Scottish parliaments in the English Civil War. After his defeat in 1645, he surrendered to a Scottish force that eventually handed him over to the English Parliament. Charles refused to accept his captors’ demands for a constitutional monarchy, and temporarily escaped captivity in November 1647. Re-imprisoned on the Isle of Wight, Charles forged an alliance with Scotland, but by the end of 1648 Oliver Cromwell’s New Model Army had consolidated its control over England. Charles was tried, convicted, and executed for high treason in January 1649. The monarchy was abolished and the Commonwealth of England was established as a republic. The monarchy would be restored to Charles’s son, Charles II, in 1660.“
Source: Charles I of England

“Louise Marie-Thérèse, also known as The Black Nun of Moret (c. 1658 – 1730), was a French nun and the subject of accounts from the 18th century in which she was dubiously claimed to be the daughter of the Queen of France, Maria Theresa of Spain. Her existence is mentioned in several different sources. The Black Nun of Moret, Louise Marie-Thérèse (1664–1732), was a Benedictine nun in the abbey of Moret-sur-Loing. She was called the “Mauresse de Moret” (“Mooress of Moret”), and a portrait of her exists in the Bibliothèque Sainte Geneviève in Paris. Research done by the Société de l’histoire de Paris et d’Ile-de-France, published in 1924 by Honoré Champion éditions, concluded that this pastel portrait was painted around 1680 by the same hand which painted the series of 22 pastel portraits of Kings of France, from Louis IX to Louis XIV, between 1681 and 1683 on the initiative of Father Claude Du Molinet (1620–1687), librarian of Sainte Geneviève abbey. Several writers from the time have devoted paragraphs to her: she is mentioned in the memoirs of Madame de Maintenon, the Grande Mademoiselle, Madame de Montespan, Duke of Saint-Simon, Voltaire, Cardinal Dubois, and in the Journal of the Duc de Luynes.”

Shortly after the death of the French Queen Maria Theresa of Spain, wife of Louis XIV, in 1683, courtiers said that this woman could be the daughter, allegedly black, to whom the Queen gave birth in 1664. The nun herself seemed convinced of her royal birth, and Saint-Simon states that she once greeted the Dauphin as “my brother”. A letter sent on 13 June 1685, by the Secretary of the King’s Household to M. De Bezons, general agent of the clergy, and the pension of 300 pounds granted by King Louis XIV to the nun Louise Marie-Thérèse on 15 October 1695, “to be paid to her all her life in this convent or everywhere she could be, by the guards of the Royal treasure present and to come”[ suggest that she may, indeed, have had royal connections. The duc de Luynes claimed that she was the daughter of two black gardeners, too poor to educate her, who applied to Mme. de Maintenon for patronage. She died at Moret-sur-Loing.

Source: Louise Marie Thérèse (The Black Nun of Moret)

Perhaps the boy could have been sired by Charles II
“In the case of Charles II are we supposed to believe that the boy who was so dark his own mother said “he was so dark that she was ashamed of him” and never got lighter is the boy portrayed here”

“Note the boy in front wearing the semblance of a crown on his head, holding the crown pointing upwards “through the hole” so to speak, below a part of the gown made to resemble or concealing an outstretched leg of the duchess. And behind is another boy spying on from behind the pillar which has a fleur-de-lis wrapped around it. You can rest assured that this not the only painting of a mistress of Charles II or Louis XIV featuring a black boy in it.”
“Another interesting fact concerning Louis XIV, the Sun King, and first cousin to yours truly. When the tombs of the French kings were desecrated during the French revolution, guess what was noted? The body of Louis XIV was described as black like ink, all over, and what was notable about it was that it was remarkably well preserved. Yes, yes, yes. The last time the person of Louis XIV was observed, it was that of a Negro male. I suggest doubters do some research on this one before assuming that the notion that Europe’s nobility were black is a totally unfounded one. As the saying goes, denial is not a river in Egypt.”
Source: Frank Church Where is the evidence king Charles II was a black man?
“DNA from one of Britain’s fist people, Cheddar Man, shows that he was very likely to have dark brown skin and blue eyes. And, despite his eponym, we also know from his DNA that he couldn’t digest milk. While it’s fascinating, and perhaps surprising, to learn that some of the first people to inhabit the island that is now known as Britain had dark skin and blue eyes, this striking combination is not altogether unpredictable given what we’ve learnt about Paleolithic Europe from ancient DNA. Dark skin was actually quite common in hunter gatherers such as Cheddar Man who were living in Europe in the millenia after he was alive – and blue eyes have been around since the Ice Age.”
Source: Five surprising things DNA has revealed about our ancestors