Order and strict principles are vital to Mrs Fillyjonk. She doesn’t want her children to learn bad habits and gets worried if they play too boisterously. Mrs Fillyjonk wants her rules and principles to be obeyed to the letter. Even the smallest misfortunes depress her and she can easily lose her temper. Although Mrs Fillyjonk is dutiful to the point of tedium, deep inside she is perhaps a little jealous of how carefree the Moomin family is.
Mrs Fillyjonk always wears a red dress and a hat. She lives with her three children in Moominvalley, in a house surrounded by a neat fence. She first appears in the picture book The Book About Moomin, Mymble and Little My.