In Malory, a knight in Arthur’s service who was the cousin of Lamorat.

When Lamorat was slain by Gawain and his brothers, Pionel devised a plot to kill Gawain. Guinevere hosted a party, and Pionel poisoned some fruit intended for Gawain. An unlucky knight named Patrise ate the fruit instead of Gawain and died.

Sir Mador, Patrise’s cousin, accused Guinevere of murder, but Nimue eventually arrived at court and explained the truth. By this time, Pionel had fled the court.

The Vulgate Mort Artu calls the same character Avarlan.