It would be difficult to imagine a more conspicuous or thrilling big-screen debut for a child actress than that of St. Louis-born Taylor Momsen, selected out of innumerable hopefuls at six years old to play Cindy Lou Who in Ron Howard's colorful holiday fantasy How the Grinch Stole Christmas (2000). The Momsen was already an on-camera veteran when she signed for the part (given her appearance in a Shake 'n Bake commercial at three years old, and one-shot roles on the series Early Edition and Cosby), The Grinch nevertheless heightened her exposure.
Not long after The Grinch, Momsen stuck with the same genre: the family-oriented fantasy Hansel & Gretel (2002), which sported Lynn Redgrave. That very same year, however, the pint-sized ingenue returned to A-list material with small contributions to two acclaimed blockbusters: Mel Gibson's military drama We Were Soldiers and the can't-miss sequel Spy Kids 2: The Island of Lost Dreams (2002), directed by Robert Rodriguez. Her next major cinematic contributions arrived in 2007, with turns in the FX-heavy canine superhero picture Underdog and Gus Van Sant's coming-of-age drama Paranoid Park.
Despite all of her work in high-profile films, Momsen broke through to mainstream notice in 2007 via her involvement in a prime-time teen soap opera: the CW's Gossip Girl. On that series, the actress played Brooklyn-dwelling wannabe social climber Jenny Humphrey (younger sister of Dan), who was a good girl at heart but flirted with misbehavior in her quest to become part of the rich-girl clique at her prep school. In 2008 she appeared in Spy School.