Susan Foreman (Tick-Tock World)

When the TARDIS was drawn to and destroyed on a world where time was in a constant state of flux, Susan became the last survivor of the crew when the First Doctor, Ian, and Barbara were devoured by the Xesto, creatures that consumed time and all other possible futures. She escaped the creatures for some time by hiding in a Zero Cabinet, but was eventually driven to such despair that she accepted death as she had nothing else to live for. However, the nature of "death" on this world meant that Susan was subsequently left trapped outside of time itself, allowing her to eventually make contact with the "spirit" of her grandfather after he was consumed by the Xesto. Although she failed to help her past self devise a plan to escape that world, the Doctor eventually convinced the two Susans to make contact, the resulting explosion caused by their violation of the Blinovitch Limitation Effect allowing the future Susan to reach back in time and help the Doctor avert the original crash. (AUDIO: Tick-Tock World)