Sarah Jane Smith

Sarah Jane Smith, occasionally rendered Sarah-Jane Smith, was an investigative journalist who travelled with the Doctor in his third and fourth incarnations. She reunited with him in his tenth incarnation and had adventures with him and his immediate successor. Sarah Jane met nine of the Doctor's incarnations in total: those already mentioned and the First, Second, Fifth, Sixth, and Seventh. Due to her experiences with the Doctor, she was entrusted with the task of protecting Earth from hostile extraterrestrials and helping peaceful aliens. She shared these adventures with her young companions/surrogate family.