Anna was a companion of the Doctor. (ST: Good Companions)
Behind the scenes
Little is known about the Doctor to whom she was a companion — other than that he had red hair. He is assumed to be a future incarnation, rather than one from an alternate dimension.
- Because her story appears in a piece of licensed fiction and is not explicitly stated to be outside the normal DWU, she's assumed to be a genuine part of the DWU.