The Lady, aka Dorotea Senjak, is one of the principal characters in The Black Company series of military-fantasy novels by Glen Cook.
She is considered to be the most powerful sorceress in the world and appears as a stunningly beautiful and slim woman despite being over 500 years old and having been dead for a while. Along with her sisters Credence, Ardath and Sylith, she was one of the four daughters of Baron Senjak, all of whom were also legendary beauties. Her mother was the origin of the Sleeping Beauty legend except that unlike the legend we know, she never woke up. Baron Senjak repeatedly impregnated her anyway. The Lady killed at least one of her sisters and took the name of Ardath, as the knowledge of a magic practitioner's true name can lead to having that magic ability forcibly stripped. Her sister Sylith became one of The Taken, the sorceress named Soulcatcher.
She married a powerful sorcerer named The Dominator and the two established a powerful, yet authoritarian empire called The Domination. Although The Dominator was more powerful in terms of magical ability, The Lady was superbly skilled in administration and military strategy, able to keep the empire running and expanding smoothly. They are eventually defeated by the original White Rose.
By force of will and guile, she was able to convince the wizard Bomanz to resurrect her and the rest of The Taken, ten other powerful sorcerers who were her principal aides. She eventually falls in love with Croaker, the annalist and physician of the Black Company, who had been hired by Soulcatcher as an enforcement body, despite the fact that the Company was secretly protecting the new White Rose, who was pledged to destroy her. The Lady allies briefly with the White Rose to prevent the resurrection of The Dominator, who was the more serious threat, after which both lose their power.
Croaker and The Lady later have a child, the Daughter of Night, who is tapped before birth as the messenger of the demon goddess Kina. After Kina's defeat, Croaker, in his new incarnation of the demigod Shivetya, restores The Lady's magical powers.
The story of Croaker and The Lady is the dominant theme through the Black Company novels, turning from infatuation on Croaker's part and curiosity on The Lady's part to genuine affection and love in the face of the greatest of obstacles.