What is the only surviving play manuscript believed to be in Shakespeare's handwriting?

Sir Thomas More is the only surviving play manuscript generally believed to contain Shakespeare's handwriting. The manuscript is a collaborative working script about the life of the Tudor statesman and Catholic martyr Thomas More. Most of it was written or revised by other dramatists, including Anthony Munday, Henry Chettle, Thomas Heywood, and Thomas Dekker.

Shakespeare's contribution is associated with Hand D, a three-page addition containing about 147 lines. Paleographic and stylistic comparisons led many scholars to identify this hand as Shakespeare's, and the attribution has been accepted by major reference works and the British Library. The manuscript is now preserved as Harley MS 7368.

The wording “believed to be” is important. The attribution is highly influential but not absolutely uncontested. Some scholars have argued that the surviving samples of Shakespeare's unquestionably authentic handwriting—mainly signatures—are too limited for a certain comparison. The manuscript is therefore best described as Shakespeare's only surviving literary manuscript by general scholarly consensus, rather than as an identification beyond all dispute.