Mrs Mason is the wife of Mr Mason, a rich Muggle builder, who was terrified of birds. She was invited along with her husband to Number 4, Privet Drive for dinner with Vernon Dursley and his family, who hoped that Mr Mason would order a large number of drills from Vernon's firm, Grunnings. There she met his wife Petunia and their son, Dudley.
The evening started off well, however Vernon's nephew Harry Potter (who neither Mr nor Mrs Mason knew anything about) unintentionally caused a disturbance when a house-elf called Dobby made a lot of noise in his room and destroyed the magnificent pudding Petunia had prepared. Some ice-cream saved dessert, however when an owl flew straight into the living room dropped a letter on her head. She ran screaming from the house, yelling about lunatics. Her husband followed after explaining about her phobia of birds.
 Portryals within films
Mrs Mason is portrayed by Veronica Clifford in Harry Potter and the Chamber of Secrets. During the film version, rather than the pudding smash to the floor in the kitchen, Dobby made it fall on top of Mrs Mason's head.