Fans of the popular British television series “Doctor Who” landed at the Hyatt Regency in Hauppauge for the fourth annual Long Island Who convention.

About 1,500 “Whovians” attended three days of panel discussions, shopped for memorabilia and took photos with props from the long-running science fiction franchise, which chronicles the adventures of the Doctor. The time-travelling alien known as a Time Lord fights evil throughout the universe, regenerating himself as different men played by a series of actors and now in his twelfth incarnation.

“It’s a really fun expression of fandom and a very positive environment, where people are free to dress the way they want to dress and enjoy themselves,” said Ken Deep, the showrunner of the convention, which started Friday.

Panel talks about everything from how to create your own elaborate Who-inspired costume to diversity in the Doctor Who universe were held in conference rooms throughout the hotel.

Several actors from the series, which aired from 1963 through 1989 and was revived again in 2005, sat in, including Colin Baker, who played the sixth incarnation of the Doctor.

“It’s wonderful that these guys are here and excited about something I did in the ’80s,” Baker said in between signing autographs.

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Vendors assembled in another room to sell Doctor Who comic books, mugs, T-shirts decorated with quotes from the show and even handcrafted soaps molded into the shape of the TARDIS, the Doctor’s space ship.

Nearby, two life-size Daleks — one of the Doctor’s alien foes – screeched its catch phrase “Exterminate!” One of the robot-like creatures was built by hand by Charlene Dodge, of Albany, who travels with her creation to conventions across the country.

“It’s fun to interact with people and bring to life something that’s given fans nightmares for years,” Dodge said.

Evan Hillel, 27, of West Babylon, has attended the Long Island-based convention for the past three years, and was dressed as the tenth incarnation of the Doctor played by David Tennant.

“Seeing all the props and fans and great costumes has been really amazing,” said Hillel, while standing in line to take a photograph with the TARDIS control console, a prop used in the 1996 movie based on the show.

Valerie Acklin and Birgit Pols, both from Bellmore, spent days laboring over their costumes. Pols went as Madame Vastra, one of the Doctor’s longtime allies, a lizard woman with a scaly green face wearing an elegant floor-length dress, while Acklin dressed as her human wife, Jenny Flint.

“It’s so great to get to know other Whovians and being able to sit down with them and have this instant connection,” said Acklin, who has been a fan of the show for decades.