K-9

K-9 is a robot dog created by professor Marius and is given to the Doctor after he helped defeat an alien virus. There have been a few versions of K-9. One of them stayed on Gallifrey with Leela,another one travveled with Romana and the third,possibly the last,the Doctor gave to Sarah Jane Smith. K-9  still lives with Sarah Jane on Bannerman Road. He protects Sarah Jane and the Doctor,whom he calles "Master"

Doctor Who
K-9 is from the series "Doctor Who"