DOVER — Darth Vader, Batman and a Pokémon trainer walk into a library. Only this isn’t the start of a joke — it was the scene Saturday at the Dover Comic Con.

Thousands of science fiction, fantasy, superhero and anime fans flocked to central Dover for the second comic festival held in Delaware’s capital city. Started in 2014 and hosted by the Dover Public Library, the event drew approximately 2,500 fans last year, leaving organizers pleasantly surprised. This year, they were hoping to double that number.

While the 2014 version stayed at the library, this festival stretched across the street to Legislative Mall. Dozens of vendors sold action figures, T-shirts, posters and more, while food trucks from across the state served meals to attendees. Fans could also receive signed prints from artists and get their faces painted.

Children and adults alike, many dressed in elaborate costumes, walked from exhibit to exhibit, often stopping to gawk at booths or cosplayers — fans wearing detailed costumes. A few children were even scared by other attendees, whose apparel could perhaps be perceived as threatening to youngsters.

Some comic fans swung fake swords at one another as they engaged in LARPing, or live-action role-playing.

With free entertainment lasting the entire day, there was no better place to be.

Fourteen-year-old Jaimy Reynolds was dressed as Link, the hero of the famed “Legend of Zelda” video game series. The Dover resident was visiting the festival with her friends, who were also dressed up.

Carrying a plastic sword and wearing the green clothes characteristic of Link, Jaimy said she had visited last year as well, dressed then as Robin from “Batman.”

McKenzie Blake, 13, was dressed as Marvel’s Loki, wearing a staff she had made and an elaborate horned helmet she had purchased.

She was having fun and had received a number of compliments already, she said Saturday morning, about an hour-and-a-half after the event opened. Asked what the best costume she had seen was, McKenzie, who traveled up from Lewes, pointed to a nearby Weeping Angel, from “Doctor Who.”

The Weeping Angel was Haley Gerardi, a 20-year-old Felton resident attending her first comic con. After painting herself gray and donning a gray featureless mask, gray wings and a gray dress, she perfectly resembled one of the deadliest creatures from the popular British show.

“I can’t make it down the street 10 feet without people stopping me for a photo,” Ms. Gerardi said.

Swarmed by awed passersby, she spent several minutes taking pictures near a replica TARDIS, a phone box that the main character of “Doctor Who” uses to travel through time and space.

Just a few feet away from the TARDIS, John Shaw, of Glasgow, was selling action figures at his tent.

“I’m not a professional — I’m just a guy with too many toys,” he said with a chuckle.

Thousands of figures representing universes such as Transformers, “Star Wars,” “Pokémon” and Marvel could be had for a few bucks apiece. The items were just some of the many he has picked up at yard sales, flea markets and conventions over the years.

Mr. Shaw praised festival organizers, calling it a great atmosphere. With the temperature in the lows 80s and the sun shining, the weather was perfect, and people were clearly enjoying themselves.

Michelle Hughes, assistant director at the Dover library, was pleased with how things were progressing.

The festival was the brainchild of Kerry Hollyday, a library assistant.

She works mostly with teenagers and heard from many of them a desire for a cheap, local comic convention, Ms. Hughes said.

Dozens of franchises were represented Saturday, with “Doctor Who,” “Star Wars” and Marvel being among the most popular.

Perhaps the hub of the activity was the library. Fans browsed the booths outside, while many attendees stopped by the artist displays in the building.

Around noon, members of the 501st Legion, a large worldwide “Star Wars” fan club given a shout-out in official Lucasfilm publications, posed in their costumes at the library plaza. Fans stopped for pictures with Boba Fett, the bounty hunter made famous by “The Empire Strikes Back” and “Return of the Jedi. Meanwhile, a clone trooper wearing a uniform exactly resembling the costumes used in “Revenge of the Sith” stood by the door greeting passersby.

Dressed as an Imperial officer, Megan Mahoney, of Wilmington, reflected on the organization she’s been part of for a year.

“I joined because we’re a professional costuming organization that primarily does children charity work. We collect toys for children’s hospitals and everything and being able to come out and get pictures with the fans and everything,” she said.

After hearing about the 501st from her husband, she was intrigued. Even the requirement that members create their own costumes — Ms. Mahoney’s took about a year — left her undaunted.

“So it was one of these things where I started off helping him get dressed and it was so fun doing all this that I had to make my own,” she said.