Susan (Dr. Who and the Daleks)

The youthful Susan was the staunchest companion the human scientist Dr. Who, who invented the time and space machine Tardis. He referred to her as his granddaughter. Living with him and his other granddaughter Barbara in a cottage in England, she helped him develop the time-and-space ship TARDIS, which she later began flying on her own.

Origins
One account alleged that this Susan was a fictional version of the Doctor's granddaughter Susan, created by the Doctor himself. She, along with a fictional version of the Doctor, served as decoys to distract the Five O'Clock Shadow while the real Doctor piloted his TARDIS to safety. (PROSE: The Five O'Clock Shadow) According to another account, Susan was not any kind of real being (artificial or otherwise) but a fictional character played by Roberta Tovey in a 2065 motion picture loosely based on the real adventures of the Doctor and Susan Foreman on Skaro in 2064. (PROSE: Peaceful Thals Ambushed!) According to one account, Susan spent the early stages of her life believing that Dr. Who was her grandfather. As eventually realised by Dr. Who, he was actually her great-grandson due of the fact that Time Lords get younger with each regeneration. (NOTVALID: Doctor Who? 106)

First adventures in TARDIS
Regardless, Susan shared her "grandfather"'s genius and passion for science, and this contributed to her being a highly precocious child. She was extremely curious and fearless when it came to discovering new places. Susan helped Dr. Who construct TARDIS, and understood the theories behind how it worked.

She accompanied Dr. Who on his first trip to the planet Skaro in Tardis, as did Barbara and her boyfriend Ian Chesterton. During her travels, she met the Daleks and then an ancient Roman legion in 64 AD. (NOTVALID: Dr. Who and the Daleks, Dr Who and the House on Oldark Moor)

Further adventures with Dr Who
They subsequently travelled to Oldark Moor and met Count Tarkin. (NOTVALID: Dr Who and the House on Oldark Moor)

After Ian and Barbara had seemingly left Tardis, she and Dr. Who travelled to Mars with his niece Louise, where they once again encountered the Daleks as well as the telepathic native Martians. After Louise was captured by the Daleks, Dr. Who learned that the Martian Sphinx was in fact an ancient weapon whose secret had been forgotten. He was able to reactivate the Sphinx and used it to destroy the invading Dalek forces, only moments after he had rescued Louise from the Dalek flying saucer. (NOTVALID: Daleks Versus the Martians)

Dr. Who, Susan, Louise and a police constable named Tom Campbell later travelled to London in 2150 AD and found that it had been devastated by a Dalek invasion years earlier. Once there, she assisted in freeing Earth from Dalek occupation. (NOTVALID: Daleks' Invasion Earth 2150 A.D.)

Grown-up adventures
Susan eventually grew up and had her own adventures in TARDIS. She once once again landed the ship in the Dalek-invested 2150 Earth; she only walked out after narrowly escaping a patrol of the Red Dalek and Black Dalek with accompanying Robomen, grinning at her successful avoidance of the danger. (NOTVALID: Untitled 1)

Metafictional revelation
According to one account, Dr. Who and Susan eventually realised that they were only fictional characters within the works of the Scriptwriter. Partway through the script of what would have been a third movie with the characters, in which Dr. Who had greatly aged and was now nearly senile (though still inventive and self-reliant, notably creating himself a turbo-charged walking frame), Susan decided that she had had enough of the Scriptwriter putting them through one ridiculous situation after another — especially as, being a child actor, Susan would only get the pay on her 21st birthday. Pulling out a hammer and a wooden stake, props saved from her Grandfather's last acting job, Susan somehow reached beyond her fictionality and staked the Scriptwriter through the heart, putting an end to the Dr. Who movies once and for all. Upon reading through the unfinished script, Peter Cushing tried to "burn, drown and throttle it" but was unable to destroy it, merely losing it; it was later found and the truth discovered. (NOTVALID: Doctor Who 3 - The Third Motion Picture)

Behind the scenes

 * Susan was based on the Doctor's granddaughter Susan Foreman, who was an older and almost entirely different character. While a few reference works indicate that Susan's full name is Susan Who, this is not supported by any on-screen evidence. On-screen, her supposed grandfather was literally called Dr. Who, so if Susan's last name truly is "Who", this would imply that Dr. Who is her paternal grandfather. Although Susan is revealed to have been Dr. Who's great-grandmother in Doctor Who? 95, further complicating matters.