The quintet of colorful monsters, who reside in the hotel's "Monster Hall," appear whenever Monster Tea Time occurs (signified by Gonger). The monsters plow their way through the hotel to get to their tea, while chanting - "Ugga wugga tea time, ugga wugga clink. Ugga wugga tea time, ugga wugga drink!"
One of the monster puppets was previously used as Narf. Another is a modified version of the Herry Monster puppet. The monster's performers vary from episode to episode. Their performers include Warrick Brownlow-Pike and David Rudman.
Although they're not addressed separately by name in the series, the puppeteers named the monsters themselves - Colonel Mustard (the yellow monster), Sorbet (the orange), Lulu Lemon (the green), Berry (the blue) and Ethel Bay Mertz (the purple)