Several comics were started but never finished because of a lack of ideas or a good plot. Most of them did not go past the first page.
The Return of Dr. Disappear Edit
It was a one-page comic that never even made it to acstrong.com. It was made right after The Power of Invisibility. In it, Bad Burger is portrayed as an alien who brought Dr. Disapear and Invisibles back to Earth. They plan to steal Fred's surfboard.
The Curse of the Sand-Witch Edit
There was an idea for a comic in whitch sand-witch, an Atlantean with the power of controlling sand, with Bad Burger (also from Atlantis) as her sidekick. It never got past the introduction due to having no real plot.