"Star-crossed" or "star-crossed lovers" is a phrase often describing a pair of lovers whose relationship is said to be doomed from the start, though also encompassing different meanings. The phrase is astrological in origin, stemming from the belief that the positions of the stars ruled over people's fates. To describe a relationship as "star-crossed" is to say that it is "thwarted by a malign star", or that the stars are working against the relationship. The phrase is best known from the play Romeo and Juliet by the Elizabethan playwright William Shakespeare.
The phrase was coined in the prologue of Shakespeare's Romeo and Juliet:
"From forth the fatal loins of these two foes, a pair of star-cross'd lovers, take their life."
It also refers to destiny and the inevitability of the two characters' paths crossing each other. It usually but not always refers to unlucky outcomes, since Romeo and Juliet's affair ended tragically. Further, it connotes that the lovers entered into their union without sufficient forethought or preparation; that the lovers may not have had adequate knowledge of each other or that they were not thinking rationally.
Examples of famous star-crossed lovers vary in written work. Pyramus and Thisbe are usually regarded as the source for Romeo and Juliet, featured in A Midsummer Night's Dream. Catherine Earnshaw and Heathcliff from Wuthering Heights are considered one of the greatest love stories in literary works. The narrative tells the tale of the all-encompassing and passionate, yet thwarted, love between Heathcliff and Catherine Earnshaw, and how this unresolved passion eventually destroys them and many around them.
Lancelot and Guinevere are often remembered for their affair. Guinevere was the queen of Camelot and wife of King Arthur, while Lancelot was a trusted knight of Arthur's Round Table. In some versions of the tale, she is instantly smitten, and when they consummate their adulterous passion, it is an act which paves the way for the fall of Camelot and Arthur's death.
The legend of Tristan and Iseult (also known as Tristan and Isolde) is an influential romance and tragedy, retold in numerous sources with as many variations. The tragic story is of the adulterous love between the lovers. The narrative predates and most likely influenced the Arthurian romance of Lancelot and Guinevere, and has had a substantial impact on Western art and literature since it first appeared in the 12th century. While the details of the story differ from one author to another, the overall plot structure remains much the same.
Hero and Leander is a Greek myth, relating the story of Hero (Greek: Ἡρώ), a priestess of Aphrodite who dwelt in a tower in Sestos, at the edge of the Hellespont, and Leander (Greek: Λέανδρος, Leandros), a young man from Abydos on the other side of the strait. Leander fell in love with Hero and would swim every night across the Hellespont to be with her. Hero would light a lamp at the top of her tower to guide his way.
Pelléas and Mélisande (French: Pelléas et Mélisande) is a Symbolist play by Maurice Maeterlinck about the forbidden, doomed love of the title characters. A classical myth, was a common subject for art during the Renaissance and Baroque eras.
Troilus and Cressida is a tragedy by Shakespeare, believed to have been written in 1602. The play (also described as one of Shakespeare's problem plays) is not a conventional tragedy, since its protagonist (Troilus) does not die. The play ends instead on a very bleak note with the death of the noble Trojan Hector and destruction of the love between Troilus and Cressida.
Popocatépetl and Iztaccíhuatl refers to a number of mythical and folkloric explanations of the origins of the volcanoes Popocatépetl ("the Smoking Mountain") and Iztaccíhuatl ("white woman" in Nahuatl, sometimes called the Mujer Dormida "sleeping woman" in Spanish) which overlook the Valley of Mexico.
Layla and Majnun is a classical Arabian love story. It is based on the real story of a young man called Qays ibn al-Mulawwah from the northern Arabian Peninsula, in the Umayyad era during the 7th century. There were two Arabic versions of the story at the time. In one version, he spent his youth together with Layla, tending their flocks. In the other version, upon seeing Layla he fell passionately in love with her. In both versions, however, he went mad when her father prevented him from marrying her; for that reason he came to be called Majnun Layla, which means "Driven mad by Layla". To him were attributed a variety of incredibly passionate romantic Arabic poems, considered among the foremost examples of the Udhari school.
The Butterfly Lovers is a Chinese legend about the tragic romance between two lovers, Liang Shanbo and Zhu Yingtai. The legend is sometimes regarded as the Chinese equivalent to Romeo and Juliet.
Other classic star-crossed lovers include Devdas and Paro (Parvati) in Devdas, Paris of Troy and Helen of Sparta in The Iliad, Oedipus and Jocasta in Oedipus the King, Yusuf and Zulaikha during antiquity, Mark Antony and Cleopatra during the time of the Roman Empire, Khosrow and Shirin during the time of Sassanid Persia, Count Dracula and Mina Harker in Bram Stoker's novel Dracula, Heloise and Peter Abelard during the Middle Ages, and Emperor Jahangir and Anarkali, and Cyrano and Roxane in Cyrano de Bergerac, and Hagbard and Signy.
Prime time has had various star-crossed lovers labeled as notable and "unforgettable" love stories. IGN considers Buffy Summers and Angel from Buffy the Vampire Slayer to be one of the genre's most tragic and notable star-crossed pairings. Cole Turner and Phoebe Halliwell from Charmed, Michael and Nikita from La Femme Nikita, Kara Thrace and Lee Adama from Battlestar Galactica, and Clark Kent and Lana Lang from Smallville are other star-crossed couples from the genre.
With film or within modern novels and books, such star-crossed couples as Jack Dawson and Rose DeWitt Bukater from Titanic, Landon Carter and Jamie Sullivan from "A Walk to Remember", Anakin Skywalker and Padmé Amidala from the Star Wars saga, Ennis Del Mar and Jack Twist from Brokeback Mountain, and Jake and Neytiri from Avatar have been included. 
Role-playing video games have particularly featured star-crossed couples. Cloud Strife and Aerith Gainsborough from Final Fantasy VII have been called video games' greatest, as well as its most tragic, star-crossed love story. The couple is one of the most well-known video game couples in the history of video gaming. Zero and Iris from Mega Man X4 are another well-known example of star-crossed video game couples.
Text adventure games also have featured star-crossed couples. For example, in the popular doujin game, Umineko no Naku Koro ni, Shannon and Kanon, being lowly servants to the Ushiromiya family, are unable to join with their respective loves throughout the first arc of the game. By the end of the second arc, both couples have died together.
"Starcrossed" is a web-based reality soap opera where Fox News astrologer Greg Tufaro takes a couple in crisis and separates them for one cycle of the moon. Each is then set up with individuals who are a better match astrologically. The show puts the question "Is love written in the stars?" to the test with the couple deciding on the 28th day of their separation whether they will stay together or remain apart.