Sir John Falstaff is a fat old knight in Shakespeare. He turns up in Henry IV (both parts) and The Merry Wives of Windsor. He is a friend of Prince Hal — the young man who will become King Henry V — and he lives for jokes, food, drink, and easy money. Audiences love him because he is warm and funny. You should still not trust him with anything important: he boasts, he runs from a fight, and he bends the truth when it helps him. Shakespeare invented the character; the name belongs to the plays, not to a real knight you can look up in a history book. English later borrowed him as a picture of a certain kind of man: large, jolly, fond of wine, not strictly honest. When someone is called “a Falstaff”, that picture is what is meant.