Lady Tremaine is the main antagonist of the 1950 film, Cinderella, and it's two sequels.
Unlike most other Disney villains, Lady Tremaine doesn't possess any magical powers or exert any physical force. She strongly believes in maintaining grace and self-control, reminding her daughters of this when the two fight during their music lesson. The only time she herself breaks this rule is, ironically, at the point when Cinderella interrupts the music lesson to bring Lady Tremaine the invitation to the Royal Ball and she slams her hands onto the keys of the piano in frustration. She has a sinister glare and is very cruel to Cinderella; an example is when she silences Cinderella harshly twice when ordering Cinderella to do chores in the chateau. She even does the same to Anatasia and Drizella occasionally.
She holds a great envy towards her stepdaughter simply for her beauty, and is utterly insensitive to her, treating her like a servant in her own home, and is so deviously manipulative in controlling Cinderella by maintaining a "benevolence" in her authority of the household and never physically abusing Cinderella, instead leaving that to her daughters when they tore Cinderella's dress, and cruelly bidding her "good night" since Cinderella couldn't go to the ball in rags, ultimately maintaining her apparent fairness, and at the same time manipulating her daughters to abuse Cinderella in ways she cannot afford to do so personally.
Almost all of Tremaine's actions are motivated by a hunger for power and status, as she wants to marry her daughters off to those on the top of the social-ladder, and expects her daughters to be utterly obedient, and is infuriated when they are not, as seen when Anastasia chose not to marry Prince Charming, and Tremaine turned the Fairy Godmother's wand on her own daughter.