Daegal will be a new guest character portrayed by Alfie Stewart in Series 5. He is pretending to be a druid boy, and comes to Camelot asking Merlin for help. He appears in the episode The Hollow Queen.  According to recent articles Daegal is said to trap Merlin in a cave while Sarrum, Gwen, and Morgana are unleashing an evil plot on Camelot. It is unknown if Daegal will be aiding them.
Arrival in Camelot
Daegal is originally working with Morgana when he arrives in Camelot. He knows both her and the queen, so is pardoned when out after hours. He goes to Merlin, who is in the kitchens preparing a bath for Guinevere. Daegal shows him a druid mark on his arm, and tells Merlin that he has a sister suffering from the sweating sickness, in the Valley of the Fallen Kings . He tries to pursuade Merlin, and is told to wait at the Darkling Woods at first light.