Imps are invisible creatures that serve the most skillful witches. Queen Zixi summoned imps to weave an exact likeness of the Magic Cloak originally woven by Fairies. (Queen Zixi of Ix)
Ozma encountered a trio of visible imps named Olite, Udent, and Ertinent, who who had no respect for anyone or anything. They jeered at strangers and made faces at them, and often they pushed travelers out of the path or threw stones at them. Finally the Wizard came to her rescue and turned them into buttons. ("Ozma and the Little Wizard")