Nicholas Udall (1504-1556) was an English playwright and schoolmaster, the author of Ralph Roister Doister, regarded by many as the first comedy written in the English language.

Udall was born in Hampshire and was educated at Westminster School and at Corpus Christi College, Oxford. He taught Latin at Eton College, of which he was headmaster from about 1534 until 1541, being forced to leave when he was convicted under the Buggery Act 1533 for committing sodomy. Although the felony of buggery carried a sentence of capital punishment (by hanging), his sentence was reduced to just under a year in prison. A Protestant, he flourished under Edward VI, and survived into the reign of the Catholic Mary I.

He published several translations and commentaries for the benefit of his pupils. Ralph Roister Doister was written specifically for schoolboys to perform, but was not published until after the author's death.