Non-fungible tokens (NFTs), essentially digital versions of physical collectibles like baseball cards, are the swag du jour for Hollywood franchises looking to gin up fan excitement.

WarnerMedia’s DC announced that will give away — for free — NFTs of comic-book covers (in three different levels of rarity) for superheroes including Batman, Superman, Green Lantern, Wonder Woman and Harley Quinn. The NFT drop, set for Oct. 5, is designed to drive signups for the DC FanDome event: Users who register for FanDome at dcfandome.com (which takes place Oct. 16) can receive one free NFT, which is allocated randomly, and can unlock a second free collectible if they share their first NFT on social media.

For example, fans of the Princess of Themyscira (aka Wonder Woman) can collect NFT covers designated as “common” (1987’s Wonder Woman No. 1 by George Peréz), “rare” (2021’s Nubia and the Amazons No. 1 by Alitha Martinez), and/or “legendary” (Yara Flor on 2021’s Future State: Wonder Woman No. 1 by Jenny Frison) cover.

“We spent a lot of time on how to translate and adapt these classic covers into a 21st century format such as NFTs,” said Jim Lee, DC’s publisher and chief creative officer. “This drop pays homage to our 87-year history while visualizing a future in which NFTs play a foundational role in novel ways of interacting with DC content and unlocking new experiences.”

DC is teaming with Palm NFT Studio, which provides creative services for artists and rights holders looking to create NFTs, for the promotion. DC said it picked Palm in part because its blockchain technology uses “environmentally sustainable and energy efficient” technology to let DC mint “millions of NFTs for fans with near zero cost.”

DC and Palm aren’t revealing how many comic-book cover NFTs they plan to produce. But, according to Palm NFT Studio chief content officer Matt Mason, the rarity levels “will make the less-common NFTs more valuable, and the entire collection will grow in importance to fans as it becomes clearer that this drop represents the start of an entirely new chapter for DC Comics, and the use of blockchain as a medium for fan engagement and storytelling.”

NFTs use blockchain (a distributed ledger technology) to certify the ownership of a unique digital content asset. Palm NFT Studio recently worked with Warner Bros. to create a collection of 91,000 limited-edition NFTs featuring characters from “Space Jam: A New Legacy,” including Bugs Bunny, Tweety, Porky Pig and LeBron James — which were given out for free to fans. Other initial projects on Palm include Damien Hirst’s The Currency with HENI and Candy Digital’s digital collectible program with Major League Baseball.