First Masked Hero in Literature

I may have found him. In the 1890s a penny dreadful magazine printed a series of stories presenting Springheeled Jack as a masked champion of the people.

This predates Dr. Syn (The Scarecrow of Romney Marsh), the Scarlet Pimpernel (who wore disguises but doesn't seem to have worn a mask) and Zorro.

Are there any earlier candidates?

Let me refine my terms, here. I'm looking for the first (in terms of publication date) character who used a masked identity to fight crime and injustice. Whether a specific costume is involved is optional.

I'm also interested in the earliest setting for such characters. The Scarecrow/Dr. Syn was in the Eighteenth Century. Are there any earlier candidates?

Using the Right Words is Important

New Joy of High Tech posted at:

http://www.dcr.net/~stickmak/JOHT/JOHT56Terminology.html