- You may be looking for Astrid Ferrier.
She met the Tenth Doctor when she broke a glass and he offered to help her clean it up. She refused. When he told her he was a stowaway and she offered to get him a drink on the house, he decided to take her on a teleport trip down to Earth.
There they met Wilfred Mott, who told them people had abandoned London because of all the alien invasions at Christmas time. The Doctor and Astrid were teleported back to the ship, where the Doctor noticed that the Titanic's shields were down and three asteroids were on course to hit the ship.
He complained to the steward, but the asteroids hit the ship and killed most of the passengers apart from the Doctor, Astrid and a few others including Rickston Slade, Foon Van Hoff, Morvin Van Hoff, Mr Copper and Bannakaffalatta. They learned the Heavenly Hosts were killing all the survivors.
Though Foon, Morvin and Bannakaffalatta died along the way, the others made their way to safety. Astrid asked the Doctor if she could be his companion and he agreed. Before they parted she kissed him, claiming it was a tradition. Astrid used a teleportation bracelet to get to Deck 31 to help the Doctor.
To save the Doctor and defeat Max Capricorn, she lifted Capricorn and his life support system with a forklift and threw him into the engines. The forklift's brakes were cut by a halo thrown by a Heavenly Host. She plunged to her death along with Capricorn, but was dematerialised by an automatic function of her teleport bracelet. Using the advanced transmat system, the Doctor tried to recover Astrid, but only succeeded in creating a partially cohesive, non-corporeal form, neither truly alive nor dead. Mr Copper described it as "an echo with the ghost of consciousnes." Reluctantly, the Doctor allowed her atoms to scatter into space, fulfilling her dream of travelling the galaxy. (TV: Voyage of the Damned)
Astrid kept appearing to the Eleventh Doctor in 1963 through various objects, although this turned out to be an alien called the Shroud. It showed a vision of a person whom the victim missed a lot. (PROSE: Shroud of Sorrow)
Astrid was a feisty young woman who longed to discover the wonders of the universe and set foot on other worlds. She was thrilled when the Doctor granted her wish by allowing her to visit Earth. She was unhappy with her job as a waitress on the Titanic, where she had to put up with verbal abuse from customers like Rickston Slade.
She formed a close bond with the passenger Bannakaffalatta and was distraught when he sacrificed his life to destroy the Host threatening the survivors. She became fond of the Doctor to the point she began to experience romantic feelings towards him. They kissed twice and she ultimately gave her life to save Earth and him from Max Capricorn's plot.
Behind the scenes
Astrid was originally simply named Peth. (REF: Doctor Who: The Writer's Tale) Astrid is an anagram of TARDIS. The name Astrid (Old Norse: Ástríðr) is of North Germanic origin, literally meaning "fair goddess" (áss (goddess) and fríð (fair)). Peth is Welsh for "thing". While implying that Astrid ultimately has some connection to the Doctor's time-ship, this proved to be unfounded in the episode.
The British newspaper The News of the World released a report before Kylie Minogue was officially cast as Astrid, claiming incorrectly that her character would be a sexy Cyberwoman.
As with most "one-time" companions, Astrid's actual status as an "official" companion is a matter of debate among fans. (See also Sara Kingdom and Grace Holloway) Astrid's case is strengthened by the fact that during the course of the story she is directly invited to join the Doctor, much like Grace Holloway, and she accepts. Unlike Grace, however, she dies before setting foot in the TARDIS.