M is for... Morgaine

Battle Queen of the S'rax, Morgaine originated in an alternative dimension. In this, our Arthurian legends were real. He had been her lover, but later they became bitter enemies.

She defeated the king's magician Merlin - sealing him in an ice cavern - but Arthur fled their final battle. She despatched her son Mordred to Earth to seek him out, and he established a portal for her to follow. She brought with her The Destroyer - a powerful demon-like creature. It taunted her to release it from its silver bonds, but she wanted to keep it as a last resort. She secretly feared it could turn on her if freed.

As well as seeking revenge against Arthur she sought his sword, Excalibur, as it had strange powers, as well as operating the spacecraft which had brought him to Earth in ancient times.

Morgaine admired the Brigadier and his troops as fellow warriors, and respected the war dead of the local area. She paid for her boorish sons' drunken behaviour at an inn by curing the landlady's blindness. However, she could equally kill a UNIT soldier simply to extract information from her mind.

When Mordred was captured, she was prepared to let him be killed by the Brigadier.

On learning that Arthur was long-dead, and she could never have her revenge, she was going to trigger a nuclear war - but the Doctor convinced her that this was never an honourable mode of warfare.

She and Mordred were taken into UNIT custody.

Played by Jean Marsh. Appearances: Battlefield (1989).

• Marsh's Doctor Who connections go back to her short-lived marriage to Jon Pertwee.
• She played Princess Joanna in The Crusade (in which Nicholas Courtney came close to playing her brother King Richard - first choice if Julian Glover proved unavailable).
• With Glover's then wife, Eileen Atkins, she created period drama Upstairs, Downstairs - the Downton Abbey of its day.
• She finally got to play Courtney's brother in The Daleks' Master Plan, when she played Sara Kingdom to his Bret Vyon. They only have a single scene together - when she shoots him dead.
• Around the time the pair worked together on this story, Marsh was cornering the market in witch-like characters, having played one in Return to Oz and in Willow.