Isis
Isis is the family dog, and belongs to the Crawleys. However, she shares a very close connection to the Earl of Grantham, as she is always beside him.
Intro
Excluding the Christmas Special, Isis is shown at the very beginning of the show's introduction, walking beside the Earl of Grantham.
Series One
Isis occasionally appears in the background in Series One.
Series Two
Isis appears in Series Two when Mrs. Patmore feeds her leftover Crepe Suzettes after telling Ethel that none were left over from the previous night's dinner. She also made several background appearances.
Isobel also mentions her when she talks about the convalescent home, she asks what can be done about keeping her out of the rooms to which Robert replies "I can answer that - nothing at all"
Christmas Special
Isis appears in the Christmas Special when Thomas hides her in a shack. His plan was to keep her hidden and then find her to gain the Earl's trust, which would lead to him getting hired again. However, his plan backfires when a village girl finds Isis and brings her to the Earl for a reward. However, the Earl sees that Thomas was searching for Isis and is touched. Thomas gains his trust and is hired once again.
Series Three
Isis occasionally appears in the background.
Christmas Special 2012
Tom Branson is holding Isis on her leash when the family leave for Scotland. Robert asks him to walk her a lot, saying she can get lazy. Later he is walking her when he goes to lunch at the Grantham Arms.