In earlier mentions Tor's father is King Ars or Aries, but the Post-Vulgate Cycle and Sir Thomas Malory's Le Morte d'Arthur say this man is his adoptive father while his natural father is King Pellinore. In these versions, he is brother to Sir Aglovale, Sir Lamorak, Sir Dornar, Sir Percival, and Dindrane. He is born when Pellinore sleeps with his mother "half by force", and she marries Aries shortly afterward; here Aries is not a king, but a shepherd. Tor and his twelve half-brothers are raised as shepherds, but Tor dreams of being a knight. Finally his parents take him to King Arthur's court, and Arthur makes the boy one of his first knights. Later Merlin reveals Tor's true parentage, and Pellinore embraces his son. Neither Aries nor his wife seem offended.
Tor distinguishes himself at the wedding feast of Arthur and Guinevere when he takes up a quest to retrieve a mysterious white brachet hound that had come into the court. According to Malory, Tor and his brother Aglovale are among the knights charged with defending the execution of Guinevere; they both die when Lancelot and his men rescue the queen.