In the early days of its film division, Marvel liked to boast that it had a library of hundreds of characters like Spider-Man and the X-Men. While that's technically true, it doesn't mean that all of those characters really have the potential to headline major feature films, or Netflix TV series, or even supermarket openings. They're more "like" Spider-Man in that they also wear costumes and beat people up. At present, searching for "Speedball" in the Kindle Store gets you nothing related to the Marvel Comics character-- and that one is a little more like Spider-Man in that he was created by Steve Ditko. A search for one of Marvel's most notorious creations, NFL SuperPro, also draws a big goose egg. Micronauts? Rom the SpaceKnight? Those will get you some comics results, but none that can be read digitally... even though such comics are hard to find in print.
T Campbell has written quite a few online comics series and selected work for Marvel, Archie and Tokyopop. His longest-running works are Fans, Penny and Aggie-- and his current project with co-writer Phil Kahn, Guilded Age.