Helaine, Helayn, Helen
The daughter, niece, or wife of King Hoel of Brittany (excepting the Vulgate Merlin, where she is "an old woman" and the niece of Lionel of Nanteuil, and the Norse Saga of Tristram, where she is Duke Orslís daughter).
She was kidnapped by the Giant of Mont St. Michel. Arthur, on his way to wage war against Lucius of Rome, heard of her plight and traveled to the mountain with Kay and Bedivere. They arrived to find the lady dead - either from rape or from suicide to avoid rape - but Arthur avenged her by killing the giant. A tomb was later erected on Mont St. Michel in her memory.
The daughter of Coel who, legend says, married the Roman Emperor Constantius Chlorus after peace had been restored between her father and the Emperor, who had been besieging his city of Colchester for three years. Their son, born in AD 265, was Constantine the Great.
Helena is better known as Saint Helena, her dates being given as c. AD 255-330. Tradition makes her the daughter of an innkeeper in Bithynia. She was divorced, for political reasons, in AD 292, but when Constantius Chlorus was declared emperor by his army in York, he made her the Empress Dowager.
In AD 312, when toleration was extended to Christianity, she was baptised and in AD 326, according to tradition, she visited Jerusalem and founded basilicas on the Mount of Olives and at Bethlehem.