Taylor Michel Momsen,  frontwoman of The Pretty Reckless, played Jenny Humphrey on what CW series?
The Pretty Reckless:  The band consists of Taylor Momsen (lead vocals, rhythm guitar), Ben Phillips (lead guitar, backing vocals), Mark Damon (bass) and Jamie Perkins (drums). Taylor Momsen:  She is also known for portraying the character of Jenny Humphrey on the CW teen drama series "Gossip Girl" (2007–2012) and Cindy Lou Who in the film "Dr. Seuss' How the Grinch Stole Christmas" (2000).
Gossip Girl