Don't be fooled by the goldfish-bowl appearance, this master of smoke and mirrors is the most bewildering of all Spidey's foes. Former special effects man Quentin Beck has no superpowers but uses the art of performing-magician misdirection amazingly well.
Mysterio (Beck) on Marvel
Detailed information on the master of make-up, physical stunt work, mechanical and visual special effects on the Marvel Comics site.
Mysterio, on Wikipedia
Wikipedia entry on the Spider-Man villain. Sections: biography, powers and equipment, Mysterio in other media etc.