Perceval
Sir Perceval is the protagonist of the poem and also the titular character. He is a young knight who has just left his home to become a member of King Arthur's court. He is eager to please the king and has a tendency to show off in an attempt to impress him, but he is valiant and courageous and does not shy away from battle or conflict. In his first days at court he kills a troublesome knight and subsequently rescues another.
Perceval is devoted to his mother and devastated by her death, which is all the more devastating when he learns that she could have been saved by the power of the grail that he witnessed at the Fisher King's castle.
King Arthur
Whether he is legend or actual historical figure, King Arthur's reign as the monarch of Cornwall is both mysterious and well documented in poem and text. He is a benevolent King who treats his knights well and rewards courage and loyalty.
Sir Kay
A jealous and resentful man, Sir Kay is another of King Arthur's knights, and he appears to deeply dislike younger knights who come into the court. Because of this he is very disdainful and creates a lot of animosity that is never really forgotten by the recipients of his cruel barbs. Once a confidante of Arthur he is a troublemaker and can be disloyal.
Perceval's Mother
Perceval's mother is opposed to his becoming a knight because of the inherent dangers it holds for her son. The two are close. She is ailing and passes away whilst Perceval is at King Arthur's court.
Gawain
Sir Gawain is another young knight of the Round Table and he is actually King Arthur's nephew. He is valiant and filled with courage that he couples with his natural skill as a knight. He has a similarly bad relationship with Sir Kay to Perceval.