1. He was of Viking extraction.

Though he spoke a dialect of French and grew up in Normandy, a fiefdom loyal to the French kingdom, William and other Normans descended from Scandinavian invaders. William’s great-great-great-grandfather, Rollo, pillaged northern France with fellow Viking raiders in the late ninth and early 10th centuries, eventually accepting his own territory (Normandy, named for the Norsemen who controlled it) in exchange for peace.

2. He had reason to hate his original name.

The product of an affair between Robert I, duke of Normandy, and a woman called Herleva, William was likely known to his contemporaries as William the Bastard for much of his life. His critics continued to use this moniker (albeit behind his back) even after he defeated the English at the Battle of Hastings and earned an upgrade to William the Conqueror.

3. His future bride wanted nothing to do with him at first.

When William asked for the hand of Matilda of Flanders, a granddaughter of France’s King Robert II, she demurred, perhaps because of his illegitimacy or her entanglement with another man. According to legend, the snubbed duke tackled Matilda in the street, pulling her off her horse by her long braids. In any event, she consented to marry him and bore him 10 children before her death in 1083, which plunged William into a deep depression.

4. He couldn’t bear any disrespect toward his mother.

During William’s siege of Alençon, a disputed town on the border of Normandy, in the late 1040s or early 1050s, residents are said to have hung animal hides on their walls. They mocked him for being the grandson of a tanner, referring to the occupation of his mother’s father. To avenge her honor, he had their hands and feet cut off.

5. He made England speak Franglais.

William spoke no English when he ascended the throne, and he failed to master it despite his efforts. (Like most nobles of his time, he also happened to be illiterate.) Thanks to the Norman invasion, French was spoken in England’s courts for centuries and completely transformed the English language, infusing it with new words.

6. His jester was the first casualty of the Battle of Hastings.

William’s jester rode beside him during the invasion of England, lifting the troops’ spirits by singing about heroic deeds. When they reached enemy lines, he taunted the English by juggling his sword and was promptly killed, initiating the historic skirmish.

7. He was touchy about his weight.

Described as strapping and healthy in his earlier years, William apparently ballooned later in life. It is said that King Philip of France likened him to a pregnant woman about to give birth. According to some accounts, the corpulent conqueror became so dismayed with his size that he devised his own version of a fad diet, consuming only wine and spirits for a certain period of time. It didn’t work.

8. His body exploded at his funeral.

William died after his horse reared up during a 1087 battle, throwing the king against his saddle pommel so forcefully that his intestines ruptured. An infection set in that killed him several weeks later. As priests tried to stuff William into a stone coffin that proved too small for his bulk, they pushed on his abdomen, causing it to burst. Mourners supposedly ran for the door to escape the putrid stench.

9. He is an ancestor of millions of people.

Every English monarch who followed William, including Queen Elizabeth II, is considered a descendant of the Norman-born king. According to some genealogists, more than 25 percent of the English population is also distantly related to him, as are countless Americans with British ancestry.

10. He’s responsible for scores of British Wills.

William, an Old French name composed of Germanic elements (“wil,” meaning desire, and “helm,” meaning protection), was introduced to England by William the Conqueror and quickly became widespread. By the 13th century, it was the most common given name among English men. Today it still ranks in the top 10, and some have predicted that the future crowning of another King William will propel the name even higher.