Question: Rosaleen was a name that was possibly taken from the unseen character in which 1597 play?

Context paragraphs:
Alexei Volkoff: Alexei Volkoff (Russian: Алексей Волков ) is the alias and alter ego of Hartley Winterbottom (codename Agent X), a fictional character on the television series "Chuck".  Volkoff is the head of Volkoff Industries.  For the first six episodes of the fourth season, he was an unseen character, directing his operatives from behind the scenes.  He first appeared in the seventh episode, "Chuck Versus the First Fight".  For the first twenty-one episodes of the season, Volkoff is presented as the character's actual identity. " Chuck Versus Agent X", however, reveals that Volkoff is actually a cover, which, following a botched Intersect upload, Winterbottom unknowingly adopted as his true identity.  Volkoff serves as the main antagonist for the first half of season four and tragic character in the second half.  He is portrayed by Timothy Dalton.

Aphrodite Aperyi: Aprodite Aperyi is a fictional character on the ANT1 television series "Erotas", played by Vasia Panayopoulou.  She is one of the four leading characters of the show, however she has been an unseen character throughout much of the 3rd season having not been seen onscreen since early October.

Herne the Hunter: In English folklore, Herne the Hunter is a ghost associated with Windsor Forest and Great Park in the English county of Berkshire.  He is said to wear antlers upon his head, ride a horse, torment cattle, and rattle chains.  The earliest mention of Herne comes from William Shakespeare's 1597 play "The Merry Wives of Windsor", and it is impossible to know how accurately or to what degree Shakespeare may have incorporated a real local legend into his work, though there have been several later attempts to connect Herne to historical figures, pagan deities, or ancient archetypes.

Sycorax: Sycorax is an unseen character in William Shakespeare's play "The Tempest" (1611).  She is a vicious and powerful witch and the mother of Caliban, one of the few native inhabitants of the island on which Prospero, the hero of the play, is stranded.

The Mother (How I Met Your Mother): Tracy McConnell, better known as "The Mother", is the title character from the CBS television sitcom "How I Met Your Mother".  The show, narrated by Future Ted, tells the story of how Ted Mosby met The Mother.  Tracy McConnell appears in 8 episodes from "Lucky Penny" to "The Time Travelers" as an unseen character; she was first seen fully in "Something New" and was promoted to a main character in season 9.  The Mother is played by Cristin Milioti.

Unseen character: An unseen character or (in radio) silent character is a fictional character referred to but not directly observed by the audience, but who advances the action of the plot in a significant way, and whose absence enhances their effect on the plot.

Sarie Marais: "Sarie Marais" (also known as "My Sarie Marais" and pronounced "May SAH-ree mah-REH") is a traditional South African folk song, created during either the First Anglo-Boer War (c. 1880) (less likely) or the Second Anglo-Boer War (ca. 1900).  The tune was possibly taken from a song dating from the American Civil War called "Ellie Rhee" (itself perhaps a version of the traditional folk song "Foggy Dew"), with the words translated into Afrikaans.

Rosaleen: Rosaleen is an Irish female first name.  It is an Anglicized version of the Irish name Róisín, the diminutive of "rose" in the Irish language; it therefore means "little rose".  It has use in Ireland since the 16th century, possibly popularised by Rosaline in Shakespeare's Romeo and Juliet.

Rosaline: Rosaline ( or ) is an unseen character and niece of Capulet in William Shakespeare's tragedy "Romeo and Juliet" (1597).  Although silent, her role is important.  Romeo is at first deeply in love with Rosaline and expresses his dismay at her not loving him back.  Romeo first spots Juliet while trying to catch a glimpse of Rosaline at a gathering hosted by the Capulet family.

Fielfraz: Fielfraz was a Danish band, which had its heyday between 1990 and 1996.  The band members were Claus Hempler on guitar and vocals, Nils Brakchi on bass, Kenneth Priisholm on guitar (lead) and Jens Langhorn on drums.  The band's name stems from the German word for "wolverine" - possibly taken from south danish dialects.

Supporting paragraphs: Rosaleen Rosaline
Answer: Romeo and Juliet