Doctor Strange And The Mystery Kids - 1981
In late 1981, Marvel Productions hired Martin Pasko to write the Preliminary Development document for a proposed Doctor Strange cartoon to be sold to NBC for the 1982 season. Spinning off the Doctor's guest appearance in Spider-Man And His Amazing Friends.
According to Pasko when he sold the document in 2013, NBC rejected the pitch as they felt the mystical elements and the villains could be interpreted as "Satanic" and Marvel refused to water down the concepts any further.
The Mysterians - 1983
The Incredible Hulk & The She-Hulk - 1983
Written by Misty Stewart (Later Misty Taggart) in early 1983 as a means of retooling the previous year's Incredible Hulk cartoon, presumably as a last-ditch effort to persuade NBC to renew the series.
Changes included rewriting the Hulk to be less like the comics incarnation and more like the live-action TV series which had ended the year before. Also to bring back She-Hulk as a regular supporting character. (photos taken from ebay auction). https://www.ebay.com/itm/THE-INCREDIBLE-HULK-THE-SHE-HULK-1983-Unproduced-TV-Script-Presentation-Idea/124063444962?hash=item1ce2c1efe2:g:vi0AAOSwADReMAAW
"Car And Cable" 1983/84
Intended to be the next major Sunbow and Marvel co-production in 1987, promoting the new toyline. Ron Friedman and Doug Booth worked on development of a potential cartoon through the summer of 1986, with Friedman writing a three-part pilot by January 1987. Unfortunately, the dual slump in syndicated cartoon ratings and toy sales - due to oversaturation of both - led Hasbro to cancel the project and end all new funding for toy-promoting cartoons once the existing contracts for Jem and Visionaries were completed.
Siegfried & Roy
Pitch material created in 1992, intended for 65 episodes in 1993 season. The plans fell through and Marvel Productions was reorganised into New World Animation that year, taking Biker Mice From Mars forward under the new banner.
Concept art (20 pieces)
Pilot storyboard (14 pages) Will Meugniot