Based on my studies of him, there are several factors that contribute to his fame. One is his alias/nickname, "Blackbeard." The early eighteenth century marked a time when beards among European-descended people wasn't typical. His beard stood out enough to warrant being defined by it. He stood out physically among his fellow pirate leaders because of it. Second, and what appears to be the biggest reason, is his inclusion in an early chapter to Charles Johnson's General History of Pyracy. First published in 1724, the chapter was one of the pirates to be featured in the early chapters of the book. The author also wrote his history in such a way, by means of adding in fiction to what few facts he had of Edward Thatch at the time, that it attracted the attention of his audiences more than most of the other figures in his text. Finally, from a United States perspective, Blackbeard is famous because he operated out of a port in a colony that later became a state in the United States - North Carolina. Not only did he operate out of it, his last battle was there. Since he operated there, Americans probably got to hear more of his lore because of it. When you combine all three of the factors - the nickname, Johnson's history, and operating in North Carolina - I think it just happened to be the right combination to get him to the fame that he is at today. Also, we seem to know much more about pirates that were captured/ended in combat (reports from the guys who took them down and trials of the surviving pirates they captured both increase the likeliness of finding out more about these pirates).