TNT this weekend gave several surprised New York City moviegoers co-starring roles as “virtual extras” alongside Sean Bean in a promotional stunt for its upcoming drama series “Legends.”

The event, touted as the first campaign of its kind in U.S. cinemas, ran Aug. 8-10 at the Regal Union Square movie theater in Manhattan. Select patrons were pulled aside, and using a green screen and near real-time editing were then inserted into the “Legends” trailer, which ran in ad-network NCM’s FirstLook preshow program in the movies they were going to see.

The promotion ran in PG-13 and R-rated movies over the weekend at the theater from about 3:30 p.m. onward. TNT and NCM picked the Union Square theater because it’s a high-traffic location — an estimated 20,000 people saw the “virtual extras” trailers — and was showing big summer movies including “Teenage Mutant Ninja Turtles” and “Guardians of the Galaxy.”

“It’s great to watch the reactions of people when they see themselves inserted into the ‘Legends’ trailer,” said Tricia Melton, senior vice president of entertainment marketing and branding for TNT, TBS and Turner Classic Movies. “At first there’s a sense of surprise and disorientation, followed by disbelief and eventually that ‘boom’ moment when they realize what’s happening.”

According to Melton, one of the goals for the stunt was to spur fans to share the resulting “Legends” trailers (participants were emailed a copy of their personal trailer to share across their own social networks). Another social-focused campaign for the series is TNT’s Twitter and Tumblr hashtag #dontkillseanbean, a jokey reference to the fact that the thesp has died in more than 20 roles, including his two best-known turns, in “The Lord of the Rings” trilogy and “Game of Thrones.”

In addition to this weekend’s stunt, TNT is running sneak peeks of “Legends” via NCM’s FirstLook show nationwide in AMC, Cinemark, Regal Entertainment Group and other movie theaters through the end of August, as well as across NCM’s online and mobile networks. More than 20 million people nationwide are expected to see the standard trailer, according to NCM.

The companies declined to disclose the cost of the “virtual extras” promotion. Melton said it would consider staging similar in-theater promos for future TNT originals. According to NCM, any of the 1,500-plus theaters in its national digital network would be able to execute such a stunt, with the cinema-ad company providing cameras, green screen and staff to shoot, edit and digitally upload the spots to a theater’s servers.

The series is set to premiere this Wednesday, Aug. 13, on TNT. In “Legends,” Bean plays an undercover agent who is plunged into a mystery over his own identity. Based on the book by spy novelist Robert Littell, “Legends” is being produced by Fox 21, with Howard Gordon (“Homeland,” “24”), Alexander Cary (“Homeland,” “Lie to Me”) and Jonathan Levin (“Charmed”), Brad Turner (“24”) and showrunner David Wilcox (“Fringe”) serving as executive producers.

Watch TNT’s highlight reel of this weekened’s promo: