It also was considered by some to be a Lighter and Softer adaptation of Watchmen, because of the superheroes having to register with the government and go underground. Consider also the major plot point near the end of both: The Big Badattacks New York with a giant, octopoid monster. Also, it gives the same reasoning for not wearing capes.
It also may be the closest thing we ever get to a big-budget Animated Adaptation of Wicked—right down to having Idina Menzel starring as an emotionally conflicted sorceress who lives alone in a castle. Not to mention that they're both revisionist retellings of popular modern fairy tales (The Snow Queen and The Wonderful Wizard of Oz), and both of them have single-word adjectives as their titles. Quite a few people have also pointed out the rather striking similarities between both musicals' Signature Songs ("Let It Go" and "Defying Gravity", respectively).
Monsters, Inc. was called "the best movie that Jim Henson never made" by Muppet performers shortly after its release.note Appropriate, as director Pete Doctor is a huge Muppets fan and wanted to be a Muppeteer before becoming an animator
The LEGO Movie is basically an unofficial adaptation of a Monolith Soft title, especially given their affinity for adapting gnosticism-inspired themes. Given that the core plot is about the characters learning that their world is an illusion created by someone who wants to keep them oppressed, it is quite close.