Personal assistant
From Tardis Wiki, the free Doctor Who reference
A personal assistant was a person who assisted a specific individual.
There were a number of personal assistants at Torchwood One. Ianto Jones worked as Yvonne Hartman's personal assistant as well as a junior researcher; Dean was Kieran Frost; and Rachel Allan began her career as assistant to Tommy Pierce. (AUDIO: New Girl)
Bridget Spears was personal assistant to John Frobisher. Lois Habiba later became his junior PA. (TV: Children of Earth: Day One)