Henriad is a common title used by scholars for Shakespeare's second historical tetralogy, comprising Richard II; Henry IV, Part 1; Henry IV, Part 2; and Henry V.
While it is not known whether Shakespeare conceived of the plays as a cycle, these plays are often interpreted and performed in relation to each other, since they represent a continuous period of English history using recurring characters and including direct references to previous plays. The validity of the term "Henriad", however, is up for debate.
Some scholars include in the Henriad Shakespeare's First Tetralogy, comprising the plays Henry VI, Part 1; Henry VI, Part 2; Henry VI, Part 3; and Richard III.