Iseult

Her name is variably given as Iseult, Isolde, Yseult, Ysolt, Isode, Isoude, Iseut, Isaut (Old French), Iosóid (Irish), Esyllt (Welsh), Ysella (Cornish), Isolda (Portuguese, Spanish), Izolda (Serbian) and Isotta (Italian), among others.

In the prose versions, the lovers' end comes when Mark finds them as Tristan plays the harp for Iseult beneath a tree.

The cruel king stabs his nephew in the back, and Tristan, at Iseult's request, fatally crushes his beloved in a tight embrace as his final act.

During one adventure in Brittany, Tristan suffers a poisoned wound that only Iseult of Ireland, the world's most skilled physician, can cure.

In a moment of jealousy, Iseult of the White Hands tells him the sails are black, and Tristan expires immediately of despair.

In fact, while Iseult of the White Hands figures into some of the new episodes, she is never mentioned again after Tristan returns to Cornwall, although her brother Kahedin remains a prominent character.

The plot element of the fatal misunderstanding of the white and black sails is similar to—and might have been derived from—the story of Aegeus and Theseus in Greek mythology.