(This is part of a series of puzzles written for Timwi for a Secret Santa puzzle exchange, themed around various custom modules for the game Keep Talking and Nobody Explodes. No KTaNE knowledge is necessary for any of these puzzles except the final meta; each puzzle resolves to a single word or short phrase.)
The hidden word is
separating the red, green, and blue channels, revealing this pangram:
One possible set of letters in this font which overlay to produce the monochrome images is this:
For the most part, the letters in a given cell are shown in no particular order, so they will need to be unscrambled.
Descrambling (with help from comments):
MICHElango- Teenage Mutant Ninja Turtles
COWARdly lion- Wizard of Oz characters
SAMANtha- Sex and the City characters
HUMANTorch- Fantastic Four
RAVENCLaw- Hogwarts houses
DARTAGnan- Three Musketeers characters
each of these groups is three of a set of four. The missing members of each set, written here in the same way as the others of their group, are:
Taking the first letter of each missing word that would have been cut off results in the word "RHOMBUS".
Thank you to hdsdv, Stiv, Matthew Jensen, Bass, and MacGyver88 for their comments picking up where I left off!