Donna Lou Who is one of the characters of the 2018 Illumination animated film, Dr. Seuss' The Grinch, based on the book How the Grinch Stole Christmas! by Dr. Seuss.
She's also the mother of Cindy Lou Who and twin infants sons, Buster and Bean. She's voiced by Rashida Jones and she's based by Betty Lou Who and Martha May Whovier.
Every night, she works overtime as a hospital nurse until morning and tries her best to catch the bus since she's so tired. At her house, she was making breakfast, trying to get something at the sink and overworked trying to take care of Cindy and her twin infant brothers, Bean and Buster.
She really loves her children and does everything to the best of her ability to be happy especially on Christmas. Before The Grinch steals Christmas, she was tucking Cindy into bed and told Cindy that whatever she asks Santa for Christmas, it must be really important to her (which it is since Cindy’s only wish is to lighten her mother's workload since she always helps others).
The next morning when The Grinch finally steals Christmas, The Whos wake up and are shocked to see that the presents and decorations are gone.
Cindy at first believes she's to blame because she caught Santa, but Donna tells her that Christmas is more than just about presents and that Cindy's the best thing that ever happened to her since she helps her mother out with her workload and the Whos join in singing.
The Grinch and Max soon hear the singing and the Grinch is puzzled to see that they are celebrating Christmas despite his theft, but he soon listens to their singing and his small heart triples in size.
The sleigh almost falls off Mount Crumpit and the Grinch tries to save it and soon. Fred and his family come to his aid.
After securing the sleigh, the Grinch and Max go to Whoville to return the stolen items and he admits his theft to the Whos and apologizes before going back to his cave.
Feeling sorry for the Grinch, Cindy comes to invite him over to dinner at her house and he awkwardly attends. After he did, Donna was happy that he decided to come, welcome him, told him that he wear a nice necktie and told Cindy that he came.
Later, Donna was having a hard time, holding the foods until The Grinch helped her out and Donna was surprised at this by saying "Oh, that was very sweet of him".
When seated down for dinner, Donna told the Grinch if he can carves the roast beast and The Grinch said "Um, sure. Do you mind if I say a few words?" Which Donna applies "Not at all".
Then, The Grinch admits that it wasn't really Christmas he disliked but being lonely and told Donna that Cindy was the first girl who show him some kindness and thank her daughter for that which Donna hugged Cindy and smiles "That's my girl"
Then, The Grinch along with Max celebrates Christmas with the Whos and starts a new life with them, especially with Cindy and her family.