| Appeared in:
| How the Grinch Stole Christmas! (Book)
How the Grinch Stole Christmas! (Film)
How the Grinch Stole Christmas! (TV Special)
In the 2017 film, she is voiced by Kaitlyn Maher.
When the Grinch comes down the chimney to steal the house's contents, Cindy Lou is sneaking in for a glass of water. The Grinch slinks in and gets her a glass of water, takes her into her room, and finishes stealing things.
At the end, when the Grinch is about to carve the Roast Beast, Cindy Lou Who is right at his side to get her portion.
She has blonde hair, blue eyes and thick, wiry antennae.