Mary Carson in The Thorn Birds is Paddy's sister who offers Paddy a job at Drogheda. She is an imperious, controlling widow who convinced her late husband, Michael Carson, to marry her because she was a good-looking woman with brains in Australia, where there were few women. The author describes Mary as wielding as much power "as any puissant war lord of elder days." She controls people in the local society with her imperious ways.
In some ways, Mary might be compared to Sanaubar in The Kite Runner. Sanaubar is a beautiful but notoriously "unscrupulous" woman who marries Ali, 19 years her senior. Like Ali, she is a Hazara and a Shi'a. She has beautiful green eyes that have apparently tempted many men. Sanaubar, like Mary Carson, is not afraid to speak her mind, and she openly expresses her disdain for Ali, her disfigured husband. Like Mary Carson, Sanaubar is married to a man who is less clever and meeker than she is, and Sanaubar runs off five days after her son, Hassan, is born. She is, like Mary Carson, powerful and unkind.
It could be argued that Laila in A Thousand Splendid Suns does not resemble Mary Carson at first but comes to be more like her over time. Laila, who is beautiful and brilliant like Mary Carson, marries Rasheed because she can benefit in a material sense from the marriage. She is much younger than Rasheed, but she is pregnant and needs a father for her child. As she seeks to gain an advantage from her marriage, she is like Mary Carson. She, like Mary, becomes a widow when Mariam, Rasheed's first wife, kills Rasheed. Laila then has more power and is reunited with her true love, Tariq. Eventually, Laila becomes better able to steer her own destiny as Mary Carson is. You may, however, decide that other characters are more like Mary Carson.