Who wrote the major surviving French versions of Tristan and Isolde?

The major surviving French versions of the legend of Tristan and Isolde were written by two poets in the 12th century:1

• Thomas: An Anglo-Norman poet who produced an adaptation around 1170. His version is noted for softening the harshness of the original archetypal poem.21
• Béroul: A Norman poet whose work dates from slightly later than Thomas’s and is possibly a composite version.1

Both of these primary French versions exist only in fragmentary form. While other adaptations of the legend appeared throughout the Middle Ages—including various episodic poems and a voluminous 13th-century prose romance—these two works remain the principal French sources for the story.12