Though scholars disagree about the exact number of plays William Shakespeare wrote, he definitely wrote at least 37 plays. Some of these plays were collaborations, though the exact number of collaborations is unclear.
Some plays, such as "The Two Noble Kinsmen," are definitely collaborative texts, based on internal evidence as well as evidence from the time period. Other plays, such as "Henry VIII" and "Henry VI, Part I," have stylistic variations that indicate that more than one hand was involved in their composition. There are also two plays, "Cardenio" and "Love's Labours Won," which are lost, though Shakespeare's contemporaries knew of them. The plot and text of "Cardenio" may exist in substantially reworked form, in the 18th-century play "Double Falsehood."