Playwright William Shakespeare is widely acknowledged as one of the most influential writers in the English language, and his plays have been read or performed millions of times around the world. He was also quite prolific: Between about 1590 and 1613, Shakespeare wrote at least 37 plays and collaborated on several more. Yet for more than a century various researchers known collectively as anti-Stratfordians have argued that Shakespeare didn't actually write some -- or all -- of his work.