The Doctor generally travels with one or more companions.

Donna suggests that the Doctor not travel alone because he needs someone to stop him.

As with the other two stories, the Doctor travels alone.

Doctors who want to renew their license quickly can travel to Trenton and have the application processed while they wait.

Quinnis takes place before the television series, when the Doctor and Susan were traveling alone.

The Doctor travels back to the 18th and 16th century in an attempt to locate the cause of the fracture.

The Doctor then travelled around either on his own or with one-off companions.

Since 1963, the Doctor has travelled with various companions who generally serve to remind him of his "moral duty".

Emma opens the gateway and the Doctor travels through where he finds himself on a small island of land floating in a void.

The Doctor is travelling alone and already in his ninth incarnation as the story begins.