Although there is some controversy about whether William Shakespeare actually authored all of the plays attributed to him, there is no evidence to support the belief that he used someone else's work. There are a number of arguments that promote this claim, but academics generally agree that Shakespeare wrote them.
The most common argument against Shakespeare authoring his plays is that a commoner would not have been able to write quality plays, but his foundational education at Stratford Free School taught him Greek, Latin and foreign languages.
Some claim that William Shakespeare was hired as a ghost author by a nobleman to avoid the social stigma of being an author. Another theory is that Shakespeare's plays were written as political commentary and attributed to Shakespeare as part of a cover-up.