AKA Jack Nokes, John-a-nokes, John Noakes.
John Nokes is John Doe's cousin. The names John Doe and John Nokes have both been in use since at least the early 1600s, both used in the courts and in legal documents to refer to an imaginary1 or unknown person. And both were used, pretty much interchangeably, until the late 1800s, when John Nokes quietly fell out of fashion.
John Nokes has a long and complicated etymological spread. He may have started his long life as John Atten Oke, meaning John at the Oak. It was once common to pronounce, and write, names in the form of Atten-foo as a-foo; thus the first appearances of Mr. Nokes in legal documents was in the contracted form: John a-nokes. While Nokes was well-known as a legalese surname, many other Johns were making the rounds. Shakespeare referred to John-a-dreams in Hamlet (1601); George Whetstone used John-a-Droynes as a character in Promos and Cassandra (1578).
Because of his frequent appearances in the court of law John-a-nokes was often thought of as a litigious person. Somewhat surprisingly, he was also known as a rather dull country bumpkin:
"John-a-Nokes was driving a cart toward Croydon, and by the way fell asleepe therein. Meane time a good fellow came by and stole away his two horses. [John] awakening and missing them, said, 'Either I am John-a-Nokes or I am not John-a-Nokes. If I am John-a-Nokes, then I have lost two horses; and if I am not John-a-Nokes, then I have found a cart.'"
-- Anthony Copley, Wits, Fits, and Fancies (1614).
Just as John Doe has his friend Richard Roe, John Nokes had his counterpart, although his name changes from speaker to speaker; he may be named John-a-Stiles, John Styles, or Tom Styles2. Occasionally Richard Miles also made an appearance. The two often faced each other as antagonists in court, but the names were so firmly recognized as a pair that the phrase Jack Noakes and Tom Styles was sometimes used to refer to ignobile vulgus, the general rabble.
"I have no connection with the company, farther than giving them, for a certain fee and reward, my poor opinion as a medical man, precisely as I may give it any day to Jack Noakes or Tom Styles."
-- Charles Dickens, The Life And Adventures Of Martin Chuzzlewit (1844)
While John Stiles may still be used in modern courtrooms if an extra anonymous name is needed, John Nokes has gone the way of the dodo. Logophiles unearth him every so often, along with Thomas Atkins, Mrs. Harris, and other Ben Trovato personages.
1. Legal cases were just as complex back then as they are now, if not more so. I was going to explain why a court might need imaginary people, but the most common usages of them, in actions of ejectment, is actually too complex for me to understand, never mind explain.
2. Just as Nokes means 'at the oak', Stiles means 'at the Style'.
Patronymica Britannica, a dictionary of the family names of the United Kingdom
by Mark Antony Lower
An Explanatory and Pronouncing Dictionary of the Noted Names of Fiction
by William Adolphus Wheeler
The reader's handbook of allusions, references, plots and stories
by Ebenezer Cobham (1882)
Words: Their Use and Abuse
by William Mathews
The Works of the English Poets, from Chaucer to Cowper
by Alexander Chalmers