Marian, played by Lucy Griffiths, is the daughter of the former Sheriff of Nottingham. In the show Marian is twenty-one years old, and so is not referred to as Maid Marian. She was betrothed to Robin before he went to fight in the Third Crusade for five years. Angry with him for choosing war over their marriage, Marian is cold toward him when he returns and refuses to let his charm win her over. She eventually- though secretly- aids Robin and his gang of outlaws by spying on the Sheriff of Nottingham, as well as the sinister Guy of Gisborne, who blatantly has feelings for her.

Determined, too, to help those who live in poverty, Marian disguises herself as the Nightwatchman and gives food and supply to villages. Although she still has feelings for Robin, she agrees to marry Guy when King Richard returns to England in order to protect herself and her ailing father. Disguised as the Nightwatchman, she is stabbed by the unaware Guy and is cared for by Djaq, but dies soon after. However, it is later revealed that her body merely shut down due to a concoction that was given to her. After she is well again, Marian must fulfill her promise to marry Guy upon the King's arrival. When it is discovered that King Richard is an imposter, Marian leaves Guy and she and Robin attempt to expose the Sheriff's plan.

Angry that Marian did not marry him, and that Marian's father tried to overrun the Sheriff, Guy visits Marian's home and burns it down. Marian and her father are taken to the castle as prisoners. Guy, however, discovers that his feelings for Marian are returning. Little does he know that she is still spying on him and the Sheriff in the castle and that she and Robin have confessed their feelings for one another. When her father is murdered, Marian finds herself in the forest with Robin. Before finding her way back to the castle, she and Robin become engaged to marry after King Richard returns. Plans are foiled when Guy discovers the identity of the Nightwatchman. Although he initially saves her from death, Guy has enough of Marian's manipulating of him and his feelings in order to keep her place at the castle. When in the Holy Land to save the king, Marian puts herself between the wounded king and Guy. After revealing her feelings for Robin as a ploy to distract Guy, Guy stabs her with her sword and she dies.