“Apprentice” is a title held by learners of various crafts, most notably occult ones, during their apprenticeship.
Apprentice is the name of a singular pupil in a personalized relationship with a Master of the craft being learned, who imparts their knowledge onto the Apprentice, often with the aim of the Apprentice becoming the successor to the Master upon their retirement or death.
Although the term can apply to all sorts of crafts, it is most notoriously, and most potently, applied to apprentices of various schools of sorcery.
Behind the scenes
Historically an entirely mundane position in the pre-public-education system of most European countries, apprenticeships have come in recent years to be especially associated with schools of the occult; the term's usage as such within the Disney Comics universe was no doubt solidified by Mickey Mouse's status as the Sorcerer's Apprentice in the segment of the same from Fantasia, based on Goethe's poem of the same name.