Mission Destination:
Travel through space and time aboard the TARDIS, sightseeing and saving lives

Bill Potts (born circa 1991) was the final companion of the Twelfth Doctor.

When she first encountered the Doctor, Bill was working as a canteen assistant at St Luke’s University, seemingly destined for an unprivileged life. When free from work, she attended some of the Doctor’s lectures at the university. The Doctor saw her unfulfilled potential and invited her for a series of personal tutoring sessions.

Following an encounter with a time-traveling puddle that was piloted by her new crush, Heather, Bill discovered who the Doctor really was — an alien time-traveler, guarding a secret vault beneath the university campus. The Doctor later invited her to join him on a journey through space and time.

Bill Potts is the first openly gay companion to ever travel with any incarnation of the Doctor.

– Dr. Who Wiki