Glimfeather was a white owl.
Like other small talking beasts, he was much larger than owls in our world, and stood as tall as a good-sized dwarf.
Glimfeather was the only Narnian who saw Jill and Eustace fly into Cair Paravel, while everyone else was watching King Caspian set sail. When the two explained that they had been sent by Aslan on a quest to search for Prince Rilian, he went to introduce them to Trumpkin, Caspian's regent. However, he told the children not to tell the dwarf about their search for the prince.
Later that night, he snuck them out of the castle and took them to the Parliament of Owls, where he and a crowd of other owls explained that, though Trumpkin was loyal to the king, he would never let the children go on their quest. The king had forbidden anyone to go in search of the prince after many had tried and never returned, and the owls knew that Trumpkin would be too stubborn to be made to understand that it might be time for an exception. The owls also told the children the story of how Rilian had been lost in the first place.
The owls were all willing to help, but they did not dare to travel with Jill and Eustace north to Ettinsmoor, so Glimfeather and one other owl flew the children to the wigwam of Puddleglum the Marsh-wiggle, who agreed to go with the children on their quest.
After Jill and Eustace found the prince, Glimfeather brought him a message from Cair Paravel, and saw the children again briefly.
Glimfeather met Jill and Eustace again in Aslan’s Country after the destruction of the Shadowlands of Narnia.
Being nocturnal, Glimfeather was not quite himself until the sun went down, and at first glance he might seem rather stupid. However, he was a quick thinker and a good judge of character. He understood that Trumpkin, though loyal, would be too stubborn to make an exception to the rules and allow the children to leave on their quest. He sneaked the children out of the castle and took them to Puddleglum for a guide. Glimfeather was extremely loyal both to King Caspian and to Aslan, and he willingly helped Jill and Eustace without being asked, despite inconveniences to himself. Indeed, it was only because of his quick thinking that they were able to start their search at all. A certain affection grew between the owl and the children throughout their adventures together, and Jill and Eustace found in him a wise guide and a friend.