What rumors have been told about Gatsby?

In the early chapters of The Great Gatsby, Nick hears all sorts of rumors about Gatsby. In Chapter Two, for example, Myrtle's sister, Catherine, claims that Gatsby is the "nephew or cousin" of the German Emperor, Kaiser Wilhelm. 

Similarly, in Chapter Three, Nick attends a party at Gatsby's house and hears a number of other rumors about Gatsby's background. One guest called Lucille claims that Gatsby was a German spy during the war while another says that Gatsby is a graduate of Oxford university. Somebody else spreads the rumor that Gatsby has killed a man.

These wild rumors continue into Chapter Four when it is suggested by a young lady that Gatsby is a "bootlegger" while another declares that Gatsby killed a man who knew that he was "a nephew to Von Hindenberg and second cousin to the devil." 

While the rumors are varied and numerous, each one has the same purpose: it builds suspense ahead of Gatsby's introduction to the reader and, later, to how he built his immense fortune.