Cindy Lou Who is a character from Dr. Seuss' storybook How the Grinch Stole Christmas and its adaptations, including the 1966 animated short and 2000 live-action film starring Jim Carrey as the Grinch and Taylor Momsen as Cindy Lou Who. She appears in both versions and serves as the deuteragonist in both.

She first meets the Grinch when he saves her from a stamp machine in Whoville’s post office. She initially feels scared of him, but she later becomes his best friend.

When the Grinch tries to take over Whoville, Cindy Lou is the only Who who believes in him, despite his meanness. She suggests that they let him be the Holiday Cheermeister at Whoville’s 1,000th Whobilation, a Whos’ party that celebrates the holiday season.

Her idea is rejected, but she still believes in him, and when Mayor Augustus May Who is scheming to turn the Whobilation into a garbage dump and trash the town, she calls him a hero. She eventually persuades the Whos to allow him back into Whoville and spend the holiday with them, showing that family is the most important part of Christmas.

She also helps the Grinch return the gifts he stole, which leads to him inviting her and her family to his home for a roast feast. Her request for “Santa” to help lighten her mother’s workload touches the Grinch’s heart and makes him reconsider his actions, resulting in a happy ending. She even gets a kiss on the cheek from him for bringing Christmas back, and he hugs her tight.