ArtPuzzle. 1 What were their real names?

Commonly, artists use their nicknames instead of real ones. Ever so often happened that some nicknames were given by modern days historians than artists themselves. People generally prefer a shorter name, especially when their full name is long and complicated. In fact, what is in a name? Are there hidden meanings behind it? Why does an artist prefer to use pseudonyms? And here comes our ArtPuzzle. question What were theirreal names?