Anastasia Tremaine is Cinderella's younger stepsister, Drizella's younger sister, and the youngest daughter to Lady Tremaine in Disney's 1950 film, Cinderella and its two sequels, making her debut as the secondary antagonist of the first film alongside her sister Drizella and returning as a major character in Cinderella II and the tritagonist of Cinderella III.
She was voiced by the late Lucille Bliss in the first film, who also voiced Smurfette in The Smurfs series, and is currently voiced by Tress MacNeille who is also the current voice of Daisy Duck.
In the initial movie, Anastasia was portrayed as being just as selfish and spoiled as her sister, Drizella. However, her character is fleshed out considerably in Cinderella II: Dreams Come True and Cinderella III: A Twist in Time, showing that, while her sister and mother are socialites, she is more interested in finding somebody who will love her for who she is. While she is indeed ungraceful and rather unique in the first movie, as she becomes a more sympathetic character, she is portrayed as being only plain (compared to the beauty of Cinderella) rather than ugly. Her hair is seen as curly (styling into long ringlets) and red.
Anastasia makes her first appearance in the film Cinderella. Like Lady Tremaine and Drizella, she spends most of her time harassing, humiliating, and making Cinderella's life horrible. It is shown that she doesn't always get along with Drizella, and that the two are prone to arguments. Anastasia is shown to play the flute, though not necessarily well. During a lesson, Cinderella presents Lady Tremaine with an invitation from the palace. The invitation details that a royal ball is to be held in honor of the prince, and that all eligible maidens are invited. When Cinderella realizes that means she can attend, Anastasia mocks the idea. As she and Drizella are preparing, Anastasia discards a pink sash, which the mice take to use to make Cinderella a dress.
That night, Lady Tremaine points out the sash on Cinderella's dress, enraging Anastasia into tearing Cinderella's dress to shreds. Anastasia then goes to the ball, along with her mother and sister, but like Drizella, she fails to catch the Prince's eye.
The next morning, Lady Tremaine forcefully awakens Anastasia, announcing that the Grand Duke is coming to the house; He has been ordered to try a glass slipper onto the foot of every maiden, in an attempt to find the mystery girl the prince fell in love with at the ball. When the Grand Duke arrives to their home to see if the slipper fits or not, Anastasia's large foot proves to be too big to fit into a size 4 shoe.
Cinderella II: Dreams Come True
In the second movie, Anastasia is the central character of the segment An Uncommon Romance. She seems to have not changed until she meets with the town's handsome Baker, who catches her interest. However, Lady Tremaine and Drizella disapprove of the baker's commoner status, and try to make her forget about the baker. As a result, Anastasia goes against her mother for the first time. When she and the baker first meet, she is embarrassed after she is kicked by a horse. Cinderella sees Anastasia and realizes that Anastasia has fallen for the Baker, so Cinderella decides to help bring Anastasia and the baker together. Cinderella encourages Anastasia to follow her heart, and also gives her stepsister a makeover. As a result, the baker asks Anastasia to an upcoming ball, hosted by Cinderella. Though Drizella and Lady Tremaine are displeased, Anastasia is happy. Her part in the movie ends with her and the baker dancing at another ball hosted this time by Cinderella, who is seen dancing with her prince.
Cinderella III: A Twist in Time
Anastasia's largest role comes in the third and final film where she appears as a main character and anti-heroine. Following Cinderella's marriage to Prince Charming, Anastasia and Drizella are stuck doing her chores. Later, Anastasia, in an attempt to avoid more work, follows Cinderella and the Prince to a picnic held by the Fairy Godmother and the mice. She is seen climbing a tree, only to fall and unknowingly grab the wand belonging to the Fairy Godmother. She rushes back to her sister and mother and shows them the wand, saying it was the answer to their prayers. Both Drizella and Lady Tremaine are skeptical until Anastasia accidentally transforms Lucifer's body into that of a goose and the Fairy Godmother (who followed Anastasia to retrieve her wand) into a stone statue.
Lady Tremaine uses the wand to reverse time, to when the Grand Duke comes to their home with the glass slipper. Using the wand, Lady Tremaine alters the glass slipper so that it fits Anastasia. Anastasia is taken to the palace, where it is intended that she will marry the Prince. Though Prince Charming is certain that Anastasia was not the girl from the ball, his memories are altered by Lady Tremaine using the wand. Later on, Anastasia speaks with the King, who takes a liking to her. Apparently, Anastasia resembles his late wife, both in looks and in a lack of dancing talent. The king gives Anastasia a shell, which he claims is his most precious possession, as it was what made his and his wife's hands touch.
Over time, Anastasia realizes that the prince does not love her or anyone, and begins to question her mother's motives. Meanwhile, her mother's plans are revealed and the three are ordered to be arrested. Still, in possession of the wand, Lady Tremaine captures Cinderella, and transforms Anastasia into a Cinderella look-alike. At the wedding, however, Anastasia's conscience gets the better of her, and she refuses to marry the Prince, to the amazement of everyone, especially the real Cinderella. Suddenly, Lady Tremaine tries to turn Anastasia into a toad, until Cinderella steps in to defend her for her honesty. An unfazed Lady Tremaine decides to turn them both into toads, but the Prince intervenes and reflects the magic beam with his sword so that it hits Lady Tremaine and Drizella instead. Anastasia brings the real Cinderella and the Prince together and uses the wand to transform herself back to normal. Cinderella thanks Anastasia and the two reconcile, putting their animosity firmly behind them. Together, they restore the Fairy Godmother. Anastasia later tries to return the shell to the king, stating she does not deserve it, but the king allows her to keep it as he believes everyone deserves true love. She then hugs the king, who welcomes her into the royal family, and then watches happily as Cinderella and Prince Charming finally tie the knot.
At the end of the movie, Anastasia now lives at the palace with Cinderella and the Prince and is seen during the end credits in a picture with the baker from the second film, which slightly confuses when the events of each film a take place first (this can be accounted for the rewritten timeline). This saves her from becoming a scullery maid like her now-estranged mother and sister. This portrait also suggests that she and the Baker got married as he gives her a single cupcake in the painting.