- “I shall stay until the winds change.”
- ―Mary, telling Jane Banks that she refuses to leave in her own polite way
Since her debut, Mary has become one of Disney's most iconic and endearing characters. She has become a regular face in pop culture, receiving many parodies. She is notable for being one of the few live-action Disney characters to gain the critical acclaim of icons such as Mickey Mouse and Tinker Bell.
It is never explained where Mary really comes from, though she is seen sitting on a cloud above London near the beginning of the film. It is known that she has a friend named Bert, and an uncle named Albert (though it is unclear if he is her blood relative, as others call him that as well), who both live in London in 1910. She is described as being "practically perfect in every way."
As a nanny, she is fairly stern, but also kind and nurturing. She is shown to possess various magical abilities including the ability to speak to animals and transport herself and others to various places (including sidewalk chalk pictures), as well as flight. However, afterward, she will deny any usage of these powers and her many voyages and adventures, presumably to keep them a secret from the public.
Mary first appears at the beginning of the film, sitting on a cloud fixing her makeup. Later, she responds to the advertisement of Jane and Michael Banks for a kind nanny. After all the other nanny candidates are literally blown away by the wind, she quickly takes charge and effectively hires herself, much to the surprise of George Banks. He is especially confused as he had previously torn up the advertisement and tossed into the fireplace.
Mary goes up to her room and introduces herself to the children. While unpacking, she astounds them with her bottomless carpet bag, which contains such items as a hat stand, a large plant, and a lamp. She takes out her tape measure and measures the children. Michael is said to be extremely stubborn and suspicious, while Jane is inclined to giggle and to leave messes. They then ask to measure her, who complies. The tape measure shows a personalized message which says that she is "practically perfect in every way". It also has her name, which is revealed to them.
Next, Mary leads the children in a game, which turns out to be tidying up the nursery using magic. Simply by snapping, beds fold themselves, and toys put themselves away. After it is clean, Mary takes them on an outing. Though they intend to go to the park, they run into Bert, who is an old friend of Mary's. He scoffs at the mundane nature of the outing and notes that with Mary, unusual things happen. He is then able to goad her into transporting them into one of his sidewalk chalk pictures, which is the English countryside.
While Jane and Michael enjoy a nearby fair, Mary and Bert stroll through the countryside and enjoy a lunch together. However, their relationship is said to be merely platonic in nature. Later, Mary, Bert, and the children ride a carousel, and at Mary's word, the horses jump off. Eventually, Mary leads them to a horse race, which she wins handily. When asked by reporters for a word to describe her emotions at winning, she reveals her all-purpose word, "Supercalifragilisticexpialidocious". However, a rainstorm hits and washes off the drawing, forcing Mary to cut the outing short. That night the children ask her to stay forever, but she promises to only do so until the wind changes.
The next day, Mary takes the children with her to do errands, but an emergency calls them to other matters: Uncle Albert is floating in the air due to too much laughter and is unable to come down. She attempts to keep everyone calm, as the "disease" is contagious. But after Bert and the children are all affected as well, Mary allows them to have tea while floating in the air. However, everyone is able to come down after being faced with the sad thought that they must go home.
That night, worried by his children's recount of the day's events, Mr. Banks tries to fire Mary but is soon manipulated in taking the children to the bank where he works. The next day also happens to be Mary's day off, and so when the outing ends in disaster, Mrs. Banks is forced to hire Bert to watch the children. He allows them to watch as he cleans the chimney. Mary soon appears, warning them of the danger. Both fly up it in rapid succession. Mary and Bert follow, and they take the time to explore the rooftops. They meet up with Bert's chimney sweep friends, and eventually all return to the Banks' home, where everyone parties. Mr. Banks returns from work and demands an explanation, which Mary refuses to give. Later, it is revealed that as a result of what happened during the bank outing, that he had been sacked. However, remembering Mary's all-purpose word, he is able to laugh.
The next day, Mary is seen preparing to leave, as the wind has changed. However, during the night, it is revealed that Mr. Banks has had a change of heart and has decided to be a more caring father. This pleases Jane and Michael so much that they forget to say goodbye to Mary. She notes that everything is as it should be and it is implied that she has helped numerous families like the Banks. She then flies off and Bert, noticing her, asks her not to stay away too long.
In the theatrical version, like the film, Mary is hired as a nanny after the departure of Katie Nanna. She teaches the children valuable lessons in behavior, as they are portrayed as naughtier than in the film and books. She teaches them the value of looking past appearances when she takes them to see Bert. To illustrate the point, she animates the park statues. Later on, she takes the children to see their father at the bank. Though he is furious at first, the visit helps him realize just how much his values have changed and how much his kids mean to him. On the way home, she introduces them to the Bird Woman, as well as Mrs. Corry. That night, she warns Jane, who is in a temper after an outburst from her father, about controlling herself. As Mary leaves the room, the children are put on trial by their toys. When they are found guilty, Mary realizes that the Banks family has a lot to learn. To bring them to their senses, she decides to leave.
In the second act, Mary returns after the family suffers through the tyrannical behavior of Mrs. Andrews, George's former nanny. The two nannies have a face-off, with Mary being victorious. Mary and the children have another adventure with Bert, who introduces them to his chimney sweep friends. Later, when George is called to the bank, Mary follows him with Jane and Michael in tow. At the end with some regret, Mary leaves the Banks family.
Mary makes a cameo appearance in Disney INFINITY as a townsperson. In the 3DS version, when she appears, she will allow the player or the CPU to move to another space as long as there is no other character on it.
Mary is seen at all the Disney Parks around the world as a meetable character, as well as appearing in parades and shows. She is sometimes seen with Bert and/or the penguins. She is dressed in her white outfit from the Jolly Holiday musical number (though unlike the outfit from the movie, her hat cannot be taken off), though she mentions her other outfits from the film frequently to guests and does wear her nanny outfit in the film from time to time, particularly in colder Florida weather.
Mary, Bert and a few of the chimney sweepers can be seen in their own float segment of Mickey's Soundsational Parade at Disneyland.
Mary can be seen alongside Bert in Fantasmic!
- Mary was nominated for AFI's 100 Year...100 Hero and Villain list, one of three Disney heroes, along with Peter Pan and Belle. Unfortunately, none of them made the cut.
- In the opening ceremony for the 2012 Olympics, Mary was given a tribute performance in which she chased away the evil Lord Voldemort from the Harry Potter franchise with thousands of other Marys.
- In the DCOM Lemonade Mouth, when the band is lying down in Olivia White's backyard, a cloud was noticed of "An old lady with a skirt & an umbrella." This may represent Mary Poppins, as it shows her comic stance which flying.
- In the Marvel Studios film Guardians of the Galaxy Vol. 2, Peter Quill/Star-Lord remarks that Yondu Udonta's floating down to the ground makes him look like Mary Poppins. Assuming the character to be "cool" (and male), Yondu joyfully shouts, "I'm Mary Poppins, y'all!"