Sir Lionel was a Knight of the Round Table and close friend of King Arthur. He was the late father of Kayley and the late husband of Lady Julianna. He was killed by Ruber at the beginning of the film, whilst defending Arthur.
At some point in his life, Lionel married Julianna and they had a daughter, Kayley. On the day of Kayley's birth, Arthur was able to draw the sword Excalibur from its stone and was proclaimed king. Lionel joined Arthur, serving him faithfully and was knighted by him. He helped Arthur to build the kingdom of Camelot and establish peace and justice across the land. Lionel spent a lot of time at Camelot, but would return to his family's farm to be with them when he could. He was apparently supportive of his daughter's dream of becoming a knight and told her the story of Camelot's creation many times. Lionel also knew Garrett when he was a stable-boy. After Garrett was blinded in an accident, Lionel still believed in him and tried to help him achieve his dream of becoming a knight, showing him a way to fight in spite of his blindess. He also taught him the knights' oath:
United we stand,
Now and forever,
In truth, divided we fall.
Hand upon hand,
Brother to brother,
No one shall be greater than all.
One day, Lionel left the farm to travel to Camelot with other knights, for an important meeting with the king. Arthur wanted to discuss the division of land, but things turned ugly when Ruber demanded he be given more land than everyone else. Lionel defended Arthur's decision and angrily told Ruber he would "not serve a false king" when Ruber suggested he take Arthur's place. When Ruber attacked Arthur, Lionel rushed to defend him, but was struck by Ruber with a mace and killed. Fortunately, Arthur was able to fend Ruber off with Excalibur and the rogue knight fled.
After his death, Arthur and the other knights returned Lionel's body to his family, who were devastated. He was buried on his family's land, under a stone tomb with the symbol of Camelot carved on top. Arthur also presented Lionel's shield - dented from his fight with Ruber - to his widow and she kept it in her home for many years. Kayley also never forgot her father's memory and became even more determined to follow in his footsteps.
Lionel wore a blue shirt with dark blue sleeves and a dark blue collar, light blue cuffs, an indigo belt, light blue stockings, and dark blue boots with light blue crosses. he carried a blueish-gray shield with three golden rings and a golden edge. He had brown hair and eyes. He rode a brown horse.
Lionel was very brave, noble and selfless. He was very loyal and protective both of his family, and his king and fellow knights. Lionel was described by Arthur as truly upholding the beliefs of Camelot. Lionel was a compassionate man who believed that everyone had the potential to be great, in spite of what everyone else believed, and inspired great love and courage in many people, even after his death.