Emma (The Curse of Fatal Death)

From Tardis Wiki, the free Doctor Who reference

Emma was a companion of the Doctor in a possible future.

Biography

Unlike past companions, the Doctor fell in love with Emma and proposed marriage to her, indicating his intent to finally settle down. However, after a subsequent series of rapid-fire regenerations, culminating in a final, female incarnation, Emma broke off the engagement, saying the Doctor was, in every sense of the phrase, no longer the man she fell in love with. (DW: The Curse of Fatal Death)

Behind the scenes