Captain (The Stuff of Nightmares)

Captain was a wild dog from the Middle Ages] that the Fourth Doctor kept as a pet at Nest Cottage. He was later given to Mike Yates.

Meeting the Doctor
The Doctor met Captain in the Dark Ages in England. There Captain was the head of a pack of wild dogs possessed by the Hornets. Once freed from the Hornets' 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 Hornets had possessed.

Leaving the Doctor
The Doctor gave Captain to Mike Yates to look after once the Hornets had been defeated. The Doctor's reason for this was that he already had a dog aboard the TARDIS and he did not think the two would get along.

Reunion with the Doctor
The following Christmas, Captain and Mike returned to Nest Cottage to visit the Doctor and Fenella Wibbsey. There the two would get embroiled with another of the Doctor's adventures. (AG: Hornets' Nest, Demon Quest)