there are four monsters that make up the happy monster band: ink, bluz, l.o. and frred. all of the monsters' names echo their colors: ink’s trademark color is pink, bluz’s is blue, l.o.’s is yellow and frred’s is red, the main characters were designed by don carter. all four of the band members are kids, but when they sing their voices are that of tally hall. however, in the uk version of the show, when they sing they maintain their children voices.