If you happen to run into Darth Vader at Eternal Con in Garden City's Cradle of Aviation this June, he just might be your company's IT guy. Should you pass a man dressed like G.I. Joe -- that could be your kid's English teacher. These cosplaying adults take their fandom to the next level with movie-caliber costume wardrobes that can cost thousands of dollars.

Here are three local pop culture groups that you might see popping up at a Long Island event this spring.

1. 501st LEGION'S EMPIRE CITY GARRISON ("Star Wars")

Since the age of 15, Chris Feehan, 43, of Mineola has been a self-professed "sci-fi geek." During one of his convention trips he saw a group dressed up as Stormtroopers and realized he had to get involved.

"I was drawn to the armor," Feehan says. "The bad guys in 'Star Wars' are just cooler."

He feverishly put together a costume that was up to the 501st Legion's Empire City Garrison standards -- a process that can take months or even years.

"Your costume has to match the movie exactly," says Feehan, who also plays The Emperor and a Biker Scout. "Most of the time we don't just buy the costume, we have to purchase different parts little by little."

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The local branch of this international nonprofit group attends charity events taking pictures with fans and handing out trading cards, all under the authorization of Lucasfilm Ltd., according to Feehan.

"To be part of the 'Star Wars' universe for just a little bit is thrilling," says Feehan, who attends 30 events a year. "It's almost an existential experience being a Stormtrooper for a day."

The Legion gathers for armor parties and holiday dinners, where awards are given out for best costumes.

"We're a close-knit family of people with a common mentality and interest," says Feehan. "Some of them I consider my brothers and sisters."

INFO 501st.com

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2. LI GHOSTBUSTERS

Dimitrios Haritos, 32, of Selden and his brother Chris needed a Halloween costume in 2003. They got a pair of flight suits from an army/navy store, added some patches obtained from the Internet, tossed on a few web belts and became Ghostbusters. Then they headed to Home Depot to build their Proton Packs.

"We'd watch the film and pause it on the equipment," says Dimitrios Haritos. "My brother would draw out all the details as a reference."

They started by doing line entertainment at the House of the Living Dead at the former Sports Plus in Lake Grove. Today they are a foursome with their buddies Steve Carabello, 33, of Port Jefferson and Jemal Flores, 42, of Selden.

This nonprofit group turns heads by appearing at the annual car show fundraiser for St. Patrick's School in Smithtown, the Long Island Toy Show at Hofstra and annual haunted attractions at Schmitt's Family Farm in Melville and Gateway Playhouse in Bellport.

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"We like to help out wherever we can," says Haritos. "It's become something we really enjoy."

INFO longislandghostbusters.com

3. THE FINEST -- 13TH CIVIL DEFENSE MOBILE INFANTRY DIVISION ("G.I. Joe")

When Laura Conn, 32, of Merrick walked into 2012 NYC Comic-Con dressed as Scarlett from G.I. Joe in a costume she constructed herself, she was bombarded for photos.

"I couldn't move two feet," says Conn, who is such a G.I. Joe fan she is in the process of changing her first name to Scarlett.

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The pictures ended up on the Internet and The Finest -- 13th Civil Defense Mobile Infantry Division recruited her.

The question is . . . why G.I. Joe?

"I was a bit of a tomboy," says Conn, who also portrays Cover Girl and Bombstrike. "In G.I. Joe, girls weren't being rescued or sitting on the sidelines. They were doing exactly what the men were doing."

The nonprofit group, which has chapters around the globe, gathers at various East Coast conventions promoting the G.I. Joe brand. Group members even stay at Conn's home for the weekend during Eternal Con.

At the 2013 NYC Comic-Con, her then-boyfriend, now-husband Kevin Conn proposed to her dressed as the G.I. Joe character Flint. She even got married in a dress designed to look like the Scarlett costume.

Says Conn, "My bouquet was made out of comic books and a crossbow."

INFO facebook.com/thefinestcc