Captain (The Stuff of Nightmares)

 was a wild dog from the middle ages the Fourth Doctor kept as a pet at Nest Cottage. He was later given to Mike Yates to look after.

Meeting the Doctor The Doctor met Captain in the Dark Ages in England. There Captain was the head of a pack of wild dogs possesed by the Hornet's. Once freed from the Hornet's control, Captain help track them with the Doctor in the TARDIS. The Doctor then took him to Nest Cottage like he had done with other items the Hornet's had possesed.

Leaving the Doctor The Doctor gave Captain to Mike Yates to look after once the Hornet's had been defeated. The Doctor's reason for this was that he all ready had a dog aboard the TARDIS and he did not think the two would get along. (A reference to K9)

Reunion with the Doctor The following Christmas Captain and Mike would return to Nest Cottage to visit the Doctor and Mrs Wibbsey. There the two would get embroiled with another of the Doctor's adventures.