Taylor Momsen got her big break after she was cast as Cindy Lou Who in "How the Grinch Stole Christmas," the 2000 remake of the classic cartoon starring Jim Carrey. However, it wasn't until "Gossip Girl" that the young actress really became a household name.
Momsen starred as Jenny Humphrey, the naive younger sister of Blake Lively's character's primary love interest Dan Humphrey. As the CW show's seasons progressed, her character began dressing edgier, often rocking dark eye makeup and punk-inspired looks that mimicked Momsen's real-life style.
However, rumors swirled that Humphrey's dramatic antics in the script were nothing compared to Momsen's attitude on set. Deadline reported that her character would be sidelined as a series regular due to her "volatile" behavior on set.
Sources said at the time that Momsen was frustrated that the show wasn't supportive of her music career — she is the front woman of the rock band The Pretty Reckless — but featured songs performed by fellow cast member Leighton Meester in the show.
"The show will support Taylor and her music when the time is right, but her music is not ready yet," the network said in a statement at the time.
Guest star Tim Gunn, who appeared in scenes opposite Momsen in a 2010 episode, also criticized the actress' professionalism.
"What a diva," he said. "She was pathetic, she couldn't remember her lines, and she didn't even have that many. I thought to myself 'Why are we all being held hostage by this brat?"
He also said that Momsen was "always on her phone."
"At one point the director leaned in and whispered to me, 'This is day in, day out, my life,'" Gunn said. "She annoyed the entire crew."
Momsen later said that the show allowed her to be written out in order for her to pursue her music career, not that she was fired from the set for her behavior.