“Oh my God! You’re the girl from ‘The Polar Express,’” a tourist yelled at Nia Wilkerson.
Dressed in a pink nightgown, Ms. Wilkerson was dancing in front of the Christmas tree at Rockefeller Center in Midtown Manhattan for a TikTok video.
Over the course of the next two hours on Monday afternoon, dozens more people stopped and stared. Many of them filmed her from afar or asked to take selfies with her.
“Wait, are you really the girl from the movie?” a passer-by asked.
The answer to that question is no. Ms. Wilkerson, a senior at St. John’s University in Queens, was 3 years old in 2004, when “The Polar Express” was released.
The movie, a box office hit directed by Robert Zemeckis that was based on a children’s book by Chris Van Allsburg, has long drawn criticism because of its brand of motion-capture animation, which gives its characters an eerie, zombified look.
Ms. Wilkerson, 22, said that ever since she was an elementary school student in Woodbridge, Va., people had been telling her she looks like Hero Girl, a character in the film who is also known as Holly. Later, a high school crush pointed out the resemblance.
“That was heartbreaking,” she joked.
Since then, Ms. Wilkerson, who stands five foot tall, has come to embrace her digital doppelgänger. This is the fourth holiday season she has spent making TikTok videos in the guise of Hero Girl. Each year, her popularity has grown. She now has nearly a 250,000 followers.
Ms. Wilkerson said she got the idea after seeing another woman on TikTok cosplaying as the character. “But she didn’t really look like her,” she said.
In “The Polar Express,” Holly wears pigtails and a patterned pink nightgown. Ms. Wilkerson goes with a variation on the look for her TikToks.
“It’s a seasonal gig,” she said, adding that she was recently swarmed by people in Elmo costumes while making a video in Times Square.
Accompanying her on Monday were several of her St. John’s classmates, who acted as her unpaid film crew. “My friendship is my payment,” Ms. Wilkerson joked, adding she had bought the group food at the campus dining hall during the weeks of filming.
She used to suffer from social anxiety, she said, but her TikTok alter ego has helped her overcome it. “No one in New York cares,” she said. “I would never do this anywhere else.”
Ms. Wilkerson, who is studying television and film at St. John’s, has found ways to profit from her 15 minutes of seasonal fame. She participates in TikTok’s creator fund, a program that the company uses to pays certain people who make videos for the platform, she said. Musicians have reached out to her about making videos, she added. Her rate is about $250 per video, she said. Outside of the holiday season, she makes videos on other topics, but her views drop off precipitously.
While most of the feedback has been positive, Ms. Wilkerson said she no longer read the replies to her videos, after having seen too many racist comments. Still, there have been upsides to her social media fame, like a recent collaboration with @jerseyyjoe, a popular TikTok creator known for his dance moves who sometimes makes videos dressed as Hero Boy from “The Polar Express.”
After an afternoon of shooting, Ms. Wilkerson and her friends discussed their upcoming final exams while waiting for an F train on a subway station platform. Ms. Wilkerson mentioned an earlier subway video, during which she had accidentally kicked a passenger.
After boarding a rush-hour train car, they wriggled into formation to film another TikTok. One of Ms. Wilkerson’s friends, Amanda Gopie, 20, pointed at a sign that read: “Don’t be someone’s subway story. Courtesy counts.”
“That’s you,” Ms. Gopie said, to laughs from the others in the group.
As the F train rolled toward Queens, Ms. Wilkerson and her friends recorded themselves singing “When Christmas Comes to Town,” a song from “The Polar Express.”
“The best time of the year, when everyone comes home,” Ms. Wilkerson began.
As her friends joined in to form a shaky chorus, a few riders perked their heads up in recognition. One told the singers to work on their pitch. The group decided they’d try another take.