The 27-year-old actress and musician reflected on the classic 2000 film in a rare interview.
Taylor Momsen might be best known for her rock group, The Pretty Reckless, and her role on Gossip Girl, but back in 2000, she was little innocent Cindy Lou Who in the hit Ron Howard film How the Grinch Stole Christmas.
Momsen, 27, opened up about filming the Christmas classic in a rare interview for the Today show.
"I do remember having a lot of fun on that set," the actress and musician recalled, noting that the actors went to what she called "Who school" to learn how to do the film's complicated stunts.
Due to her young age, she was only about seven at the time, Momsen couldn't wear the prosthetics that the rest of the cast wore, so a line was added into the film to explain her different look.
"They wrote a line into the film, 'She hasn't even grown into her nose yet,' because I couldn't have all the [prosthetics], so they just put a little blush on my nose," she shared.
Momsen praised her Grinchy co-star, Jim Carrey, for his "incomparable" performance as everyone's favorite holiday antihero.
"I just remember he was so kind, so concerned but so methodical with what he was doing," she recalled. "Even at that young of an age, I remember watching him and thinking, 'I'm watching an artist at work.'"
Momsen admitted that she still gets people recognizing her for her role in the film, but she prefers seeing them make the connection.
"It's certainly funny now when people don't realize I played Cindy Lou Who and they might know me from my music or something and they put two and two together and you get the giant reaction of 'I can't believe that's the same girl from How the Grinch Stole Christmas!' And I get a huge kick out of that," she said. "I grew up, but I think deep down I've still got a lot of Cindy Lou Who in me."
The film also made a big impact on her life and career thanks to the song, "Where Are You Christmas?" which Cindy Lou Who sings in the movie.
"The Grinch was the first time I went into a recording studio," she said. "I'll never forget walking into this beautiful studio with a massive console in front of me and putting headphones on and singing into a microphone for the first time... It was such an impactful moment in my life. It made me go, I want to make music for the rest of my life. I love being in a recording studio."
ET spoke with Momsen back when the film was being made, where she called the process "a thrill." Watch the flashback video below for more fun from the set: