Glerk is a fictional character from the children's book series titled "The Girl Who Drank the Moon" by Kelly Barnhill. He is a large, gentle creature known as a Swamp Monster, who serves as a protector and caregiver to the magical girl, Luna. Glerk has a wise and nurturing personality, often guiding Luna on her journey. In the story, Glerk possesses magical abilities, which he uses to help those in need. He is deeply loyal to his friends and plays a crucial role in teaching Luna about her powers and the importance of love and sacrifice. His character embodies themes of friendship and responsibility.