14. Big Hero 6
Despite the fact Big Hero 6 is a superhero-inspired Disney feature, few people knew it was based on a Marvel comic. Even less people knew the team debuted in a crossover with Sunfire and Silver Samurai; mutants who regularly encounter the X-Men.
In this story, Big Hero 6 works directly with the Japanese government to stop superpowered threats. Silver Samurai orders a teenager called Hiro to join the team after recognising his aptitude for technology. Hiro declines but changes his mind after his mother is kidnapped by Everwraiths; the spirits of those who died in the atomic blasts in Hiroshima and Nagasaki.
If that sounds a tiiiiiiiny bit different to the film you saw, the comic version of Baymax is a "synthformer", so he can change his form to a human or a dragon.
The film was originally intended to be adapted faithfully from the source material, but was ultimately changed due to its dark tone not suiting a movie intended for kids.