In the First Folio, the plays of William Shakespeare were grouped into three categories: comedies, histories, and tragedies.
 The histories—along with those of contemporary Renaissance playwrights—help define the genre of history plays.
 The histories might be more accurately called the "English history plays" and include the outliers "King John" and "Henry VIII" as well as a continuous sequence of eight plays covering the Wars of the Roses.
 These last are considered to have been composed in two cycles.
 The so-called first tetralogy, apparently written in the early 1590s, deals with the later part of the struggle and includes "Henry VI, parts one", "two" & "three" and "Richard III".
 The second tetralogy, finished in 1599 and including "Richard II", "Henry IV, Part 1", "Henry IV, Part 2" and "Henry V", is frequently called the "Henriad" after its protagonist Prince Hal, the future Henry V.
Sigurd Slembe ("Sigurd the Bastard"; "slembe" may also be translated as "worthless" or "ill-disposed") is a trilogy of plays written by the Norwegian playwright Bjørnstjerne Bjørnson and published in 1862.
 It is regarded as his finest historical drama and was influenced by the works of William Shakespeare and Friedrich Schiller.
 It directly influenced Henrik Ibsen's "The Pretenders", written the following year, which explores some similar themes.
 In contrast to Ibsen's attempts to create a historical setting through artificially archaic language, Bjørnson's trilogy used contemporary language.
 The success of this approach seems to have prompted Ibsen to adopt a similarly modernistic approach to his later history plays.
Geoffrey Freshwater is an English actor.
 His television appearances include "The Government Inspector" and the recurring character of Sgt Eric Rivers in 5 episodes of "Foyle's War".
 He was also a member of the Royal Shakespeare Company, appearing in their 2007-08 "This England" cycle of Shakespeare's history plays.
Henry IV, Part I and Henry IV, Part II are 2012 British television films based on the plays of the same name by William Shakespeare.
 They are the second and third films in the series of television films called "The Hollow Crown" produced by Sam Mendes for BBC Two covering the second set of plays in Shakespeare's Henriad.
 They were directed and adapted by Richard Eyre and star Jeremy Irons as King Henry IV, Simon Russell Beale as Falstaff and Tom Hiddleston as Prince Hal.
 Much of the two films' cast and crew overlap and the plot flows directly from the first to the second.
The Hollow Crown is a series of British television film adaptations of William Shakespeare's history plays.
Shakespearean tragedy is the designation given to most tragedies written by playwright William Shakespeare.
 Many of his history plays share the qualifiers of a Shakespearean tragedy, but because they are based on real figures throughout the History of England, they were classified as "histories" in the First Folio.
 The Roman tragedies—"Julius Caesar", "Antony and Cleopatra" and "Coriolanus"—are also based on historical figures, but because their source stories were foreign and ancient they are almost always classified as tragedies rather than histories.
 Shakespeare's romances (tragicomic plays) were written late in his career and published originally as either tragedy or comedy.
 They share some elements of tragedy featuring a high status central character but end happily like Shakespearean comedies.
 Several hundred years after Shakespeare's death, scholar F.S. Boas also coined a fifth category, the "problem play," for plays that don't fit neatly into a single classification because of their subject matter, setting, or ending.
 The classifications of certain Shakespeare plays are still debated among scholars.
This England: The Histories was a season of Shakespeare's history plays staged by the Royal Shakespeare Company in 2000-2001.
 The company staged both of Shakespeare's tetralogies of history plays so that audiences could see all eight plays over several days.
 The plays staged were: "Richard II", "Henry IV, Part 1", "Henry IV, Part 2", "Henry V", "Henry VI, Part 1", "Henry VI, Part 2", "Henry VI, Part 3", and "Richard III".
Henry VI is a series of three history plays by William Shakespeare, set during the lifetime of King Henry VI of England. "
Henry VI, Part 1" deals with the loss of England's French territories and the political machinations leading up to the Wars of the Roses, as the English political system is torn apart by personal squabbles and petty jealousy; "Henry VI, Part 2" depicts the King's inability to quell the bickering of his nobles, and the inevitability of armed conflict; and "Henry VI, Part 3" deals with the horrors of that conflict.
Saturday Night Theatre was a long-running radio drama strand on BBC Radio 4.
 The strand showcased feature-length, middle-brow single plays on Saturday evenings for more than 50 years, having been launched in April 1943.
 The plays featured in the strand included stage plays, book adaptations and original dramatisations.
 For most of its history, programmes ran for 90 minutes and were largely entertainment-centred, such as thrillers, comedies and mysteries.
History is one of the three main genres in Western theatre alongside tragedy and comedy, although it originated, in its modern form, thousands of years later than the other primary genres.
 For this reason, it is often treated as a subset of tragedy.
 A play in this genre is known as a history play and is based on a historical narrative, often set in the medieval or early modern past.
 History emerged as a distinct genre from tragedy in Renaissance England.
 The best known examples of the genre are the history plays written by William Shakespeare, whose plays still serve to define the genre.
 History plays also appear elsewhere in British and Western literature, such as Thomas Heywood's "Edward IV", Schiller's "Mary Stuart" or the Dutch genre "Gijsbrecht van Aemstel".

Question: Shakespeare's history plays featured which king?
Answer: King Henry IV