Although all of Abbott Elementarys supporting characters are funny, a look back on Mr. Johnsons best quotes prove just how much the schools custodian steals the show. Abbott Elementarys entire cast of characters is hilarious. Whether it is Jacob leaping from desk to desk and killing a fad in the process or Barbara constantly mistaking black celebrities for white ones, some of Abbott Elementarys funniest moments come from its supporting stars. However, there is one figure that everyone can agree is the shows breakout character, even among a cast crowded with iconic characters like Melissa and Principal Ava.