Guinevere (Gwen), played by Angel Coulby, is Morgana's personal servant. Morgana and Gwen are more like best friends, however, Morgana describing Gwen as "the most kind and loyal person you would ever meet."
She first notices Merlin when he stands up to Arthur when Arthur is taunting a servant. When she introduces herself she admits that she thinks Merlin is brave and a real hero. Merlin is seen to be a strong advocator in Gwen's blossoming relationship with Arthur. Gwen is imperative in saving Arthur's life in "Sweet Dreams", and it is due to Merlin's convincing that she agrees to help. Due to Gwen's status she has a tendency to be subservient, but she is seen to not be afraid of standing up for her beliefs and speaking her mind; a trait admired by most around her, particularly Arthur.
She initially has little interaction with Prince Arthur and describes him as a bully, questioning the mind of whoever would marry such a person. However, following her father's death and her friendship with Merlin, Gwen's view of Arthur begins to change. Gwen has openly expressed her faith in Arthur's ability to triumph over the odds and lead the people into a new age of a peaceful Camelot. Most notably, she did so as she tended to an unconscious Arthur in the Series 1 finale. She became embarrassed however the following morning to find out that Arthur had heard what she had said. "The Once the Future Queen" again displays Gwen's ability to stand up to Arthur as when he stays at her house pretending to be a commoner, Gwen becomes aggravated when Arthur is nothing but rude to her. Affected, Arthur tries to be more considerate towards Gwen (offering to make dinner etc.), and ultimately kisses her before he goes to joust. Arthur explains at the end of the episode that his father would never approve of their relationship, something which Gwen understands.