Muriel Bagge is the series' damsel in distress, the kind owner of Courage and the hard-working wife of Eustace. She is an overweighted elderly Scottish woman who took Courage in when he was an abandon puppy.Muriel often carries a rolling pin that she hits Eustace with when he harasses Courage. She also likes tea and usually tends to her garden. Muriel even has a great fondness for cooking; however, her recipes tend to include an excessive amount of vinegar (which she swears by), much to the distaste of both her dog and husband. Most of all, she loves sitting in her rocking chair with Courage on her lap and watching television. Due to her kindness and sweet, naive nature, Muriel is an easy (and often attractive) target for villians. She is always nice to strangers, invites them into her home, and fails to see what they are plotting. Fortunately, she has Courage to save the day. Courage also helps Muriel in many of her household duties. She also knows how to play the sitar and the piano, the former which she mostly plays to relax. She is usually worried if Eustace is in trouble, as seen in the episode "Queen of the Black Puddle." In that episode, she is worried when Eustace acts strangely, and when Eustace is gone and she cannot find him, she just cries, saying that she wants Eustace back. Because Courage cannot comfort her, he manages to go and save Eustace, who has been kidnapped by the Queen of the Black Puddle. Muriel stops crying when she sees Eustace. Muriel seems to love her husband very much, though she cannot stand his mother. Muriel always tries to get Eustace to do the right thing.
- Muriel appears to loathe Eustace's mother as she refuses to visit her in Mother's Day, and disagrees with her attempt to take the Coralites' coral.
- Her blood type is "ABXYZ."
- In Remembrance of Courage Past, Muriel's hair is brown. However, when Muriel got married her hair was orange-looking, and later in her life, her hair is white.
- Muriel knows how to drive Eustace's Truck as well as her husband.
- A running gag through out the series is Muriel showing off her underwear.
- Muriel is shy.
- Muriel is more practical than Eustace.