The Second Best Thing I’ve Seen Today: Wikipedia’s List of Common Misconceptions
This is basically a college education right here.
A couple of my favorites:
It is true that mean life expectancy in the Middle Ages and earlier was low; however, many take this to mean that people usually died around the age of 30. In fact, the low life expectancy is an average very strongly influenced by high infant mortality, and the life expectancy of people who lived to adulthood was much higher. A 21-year-old man in medieval England, for example, could by one estimate expect to live to the age of 64.
Napoleon Bonaparte was not short; rather he was slightly taller than the average Frenchman of his time. After his death in 1821, the French emperor’s height was recorded as 5 feet 2 inches in French feet, which is 5 feet 7 inches (1.69 m). Some believe that he was nicknamed le Petit Caporal (The Little Corporal) as a term of affection.