Mildred is a teenage dragon trainer and current resident of Berk. She owns a Terror named Muggy.

She lives with her mother, Ursula, and her two brothers, Harry and Bob Jr (Junior). . Her father, Bob 'Sr., was killed, previous to her family moving to Berk, in an attempt to get Mildred a pet dragon. He was killed in a rock slide, and since Ursula was originally from Berk, she felt it best to move back to her home town.

Mildred was put into dragon training since her Harry has bad eye sight and Junior is/was too young to attend. This was where she met the other members of the Hairy Hooligans gang.

Mildred's pesonality is probably one of a typical teenager- impulsive and stand off-ish. She doesn't warm up to people instantly, and takes great pleasure in making dolls. She also feels the need to take the blame for her father's death since she was the one who bugged him constantly to get her a dragon, and as such, her self esteem plumeted after her father's death. She enjoys laughing and playing around, but because she constantly hides in her shell, she doesn't get the chance to do that often.

Mildred has a petite figure, or about as petite as you can really get being a viking. Her clothes are casual and make it easy for her to move around, which is essential. Her eyes are blue-green, as they resemble her father's, and her hair is a brown-red of mid back length. She typically wears earthy colors.