WHEN “WONDER WOMAN” opens next month, the film will have an “X” factor: DC Entertainment has declared June 3 to be “Wonder Woman Day,” a promotion that should not only spark interest in the character, but also spur the box office.

The superhero’s support forces will be vast. More than 2,000 comic-book shops, libraries and bookstores across the nation will participate in the Saturday extravaganza.

As part of the big push, two special issues will be offered free: a first-issue reprint of the “Wonder Woman” series by Greg Rucka and Liam Sharp, and “DC Super Hero Girls Wonder Woman Day Special Edition,” including an excerpt tease for the third young-reader graphic novel in the Shea Fontana/Yancey Labat series.

Such DC creatives as Cliff Chiang and Marc Andreyko will also participate in the Wonder Woman Day events.

The day-long promotion is especially interesting set against spasms of fan criticism that advertising for the “Wonder Woman” film hasn’t been ramped up as intensely as it might be.

[Is ‘Wonder Woman’ receiving the same advertising treatment as her Justice League peers?]

The final trailer for “Wonder Woman” — which stars Gal Gadot, Robin Wright and Chris Pine — landed this month. Ads and appearances should increase markedly ahead of the film’s June 2 release.

Read more:

Last ‘Wonder Woman’ trailer debuts — and no sign of the main villain yet