When and what is the first reference to Shakespeare as a playwright actor in London?

The first known reference to William Shakespeare as a playwright actor in London appears in a document published in 1592. The document, known as the "Henslowe Diary", is a daily record of business transactions kept by the theatrical entrepreneur Philip Henslowe.

In the Henslowe Diary, under the date of February 19, 1592, there is an entry that mentions Shakespeare as one of the actors who performed in a play called "Henry VI, Part 1" at the Rose Theatre. The entry reads as follows:

> "Rd. at Henery the vjth the firste parte the 19 of Febreary, 1591[i.e., 1592] in the afternone, to Kydde, Marley and Shakespeare vjs"

This entry indicates that Shakespeare was an actor in the Lord Strange's Men, one of the acting companies that performed at the Rose Theatre in the early 1590s. The entry also suggests that Shakespeare may have been a relatively established member of the company, as he is mentioned by name alongside the more famous playwright Thomas Kyd and actor Edward Alleyn.

The Henslowe Diary provides valuable evidence of Shakespeare's early career as an actor in London and also confirms the date he was working with the Lord Strange’s Men acting company.