Mister Boss is a dwarf who claims to be an immortal being sent to Oz to prevent the Grimmerie from returning to Earth. He owns and operates the Clock of the Time Dragon.

In Out of Oz, he becomes part of the "accidental family" for Rain, although he loses none of his blunt attitude. He eventually marries Sister Apothecaire (calling her Little Daffy) after she leaves the mauntery. He has strong feelings towards the Clock of the Time Dragon and is deeply upset when it refuses to speak to him anymore. After its destruction he becomes very silent, which most of the characters pick up on, but thanks to his wife he manages to gain a new sense of purpose. He travels with Brrr to Munchkinland to rescue Dorothy Gale.