Sir Ector was one of Uther Pendragon's knights. He is heavyset in appearance with red hair and a primitive attitude; preferring more practical concepts like fighting and war training over educational pursuits. At some point, he adopted the orphaned Arthur but cared very little about him beyond the obligation of guardianship, treated him more as a servant and derisively calling him the Wart, while doting on his birth son Kay. He is extremely distrustful of magic and thus of Merlin, whom he mistakenly refers to as Marvin. After Arthur is revealed as the rightful King of England, he regrets his mistreatment of the boy and (out of fear of his former charge's reprisal) begs for Arthur's forgiveness.
Sir Ector first appears in his castle, worried about Wart, who has disappeared into the woods earlier in the day. He scolds Kay for allowing Wart to go into the forest alone, though Kay insists that it isn't his duty to look after Wart. Ector notes that he adopted Wart and so he feels responsible for the boy's safety. When Wart returns along with a wizard named Merlin and his pet owl, Archimedes, he gives Wart 4 demerits for his misbehavior. Though he initially refuses Merlin's (whom he keeps on calling "Marvin" by mistake) offer to educate Wart, he is quickly convinced otherwise by a display of magic. Later at night, Ector's friend, Sir Pellinore appears with news of a tournament on New Year's Day. Ector decides that Kay should be knighted and entered, as the winner's prize is ascension to the throne of England, and the Wart will accompany them as Kay's squire.
Ector is seen early the next morning, training Kay unsuccessfully. Later that day, after Wart returns from his lesson with Merlin, Ector punishes Wart for the strange story the young man tells about the lesson and for his tardiness. Later, upon finding the Wart has snuck off with Merlin again, he finds the kitchen to have been bewitched by Merlin due to the Scullery Maid telling him. Ector and his son, Kay attack the bewitched dishes, but the dishes push Ector in the washing basket and Kay is attacked by a broom and a mop. Merlin and Wart arrive to the kitchen and Merlin stops the magic dishes, turning them back to normal and Ector accuses Merlin of using black magic. After Merlin disappears and when the Wart defends Merlin, Ector angrily piles on demerits for punishment and finally revokes Wart's privilege of being Kay's squire, giving the position to a person named Hobbs.
However, after Kay is knighted at Christmas, Hobbs catches the mumps. So, Ector is forced to reinstate Wart as Kay's squire. In London, Ector later attends the tournament and is shocked when Wart is revealed to have pulled the legendary Sword in the Stone, which is supposed to reveal the rightful heir to the throne. Wart had discovered the sword and had intended to use the sword as a replacement for Kay's sword, which Wart had forgotten to bring. Everyone starts laughing at this event; making Ector and Kay think Wart is making a fool out of them. Ector returns the sword to the stone and asks Wart for the miracle. Unfortunately, Wart is interrupted by Kay; stating "anyone can pull it once it's been pulled", a fact proven wrong. Ector encourages Kay to pull the sword with all his might; hoping to have his son made the new king of England and even helps him in the process. Then, other knights join in. A knight named Sir Bart states this isn't fair and Sir Pellinore suggests they let Wart try it first which of course, Sir Bart agrees to: "That's what I say: Give the boy a chance". After Wart removes the sword yet again, the miracle is fulfilled. Sir Bart asks Ector for the boy's name. Sir Ector almost calls him Wart, but catches himself and calls the boy Arthur. Ector kneels at Arthur's feet and begs for forgiveness for his mistreatment, to which Arthur says is not necessary. He then orders Kay to bow down before his new King as well.
Sir Ector was constantly thought to be the main antagonist of the film.
The animation of Sir Ector accidentally bumping his sword into Sir Kay's head and Sir Kay moaning in pain when trying to attack the enchanted kitchen supplies is recycled from One Hundred and One Dalmatians when Horace accidentally strikes Jasper in the head with a chair leg. Archive audio of J. Pat O'Malley, who voiced Jasper, is used for Sir Kay in the scene.