Marvel Comics is offering free downloads of more than 700 first issues of many of the company's favorite superhero mags at no charge. The promotion began Sunday and runs until 11 p.m. ET on Tuesday.

The announcement was made Sunday at the South by Southwest Interactive Festival, as the Disney-owned comics titan unveiled several digital initiatives. Historic issues based on classic characters in the Marvel pantheon including Spider-Man and Iron Man will be available, as well as contemporary titles like "Civil War" and "Astonishing X-Men."

"We hope that new fans find their favorite big-screen heroes and see what's inspired all the hit films, but also hope longtime fans take time to discover a new series or character they'd never considered," said David Gabriel, Marvel's senior vice president of sales, print and digital media.

The downloads are available via the Marvel Comics app and Marvel Comics Digital Comics Shop. After Tuesday, they’ll be sold for $1.99 to $3.99 per issue.

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Among the new offerings announced Sunday is a new weekly show called “Earth's Mightiest Show,” hosted by Blair Butler, a comedian and former correspondent on G4's “Attack of the Show." Butler (photo above) will offer insights into the world of Marvel, from comics to upcoming films, at Marvel.com. The company currently offers two ongoing series, “Marvel Superheroes: What The –?” and “The Watcher,” also available on the site.

In addition, Marvel also said it was:

>> adding music to accompany digital downloads of its comics on smart phones and tablets;

>> launching “Wolverine: Japan's Most Wanted” on July 9, timed to promote “The Wolverine” movie, due on July 26;

>> enhancing its Marvel Unlimited streaming service so the users will have the ability to download six issues to a library that you can take with you when disconnected.