The original companion — smart, mysterious, and prone to screaming at just about everything.
Character Overview
Susan Foreman was the Doctor’s granddaughter, though if you’re looking for a detailed family tree, you’re out of luck — Gallifreyan genealogy makes less sense than UNIT dating continuity. Introduced in An Unearthly Child (1963), Susan was the show’s very first companion, and thus had the honor of being the test subject for “what happens when you shove a normal-looking teenager into a police box that’s secretly a time machine.” Spoiler: lots of shrieking, fainting, and endearingly puzzled looks at 20th-century slang.
At Coal Hill School, Susan was the suspiciously clever student who knew more about advanced science than her teachers, Ian and Barbara, could explain. Naturally, those two nosy teachers followed her home one night, and instead of finding an actual house, stumbled into the TARDIS and accidentally signed up for a lifetime of running from Daleks.
Susan was meant to be the audience surrogate: curious, brave, and often asking questions so the Doctor could deliver exposition. Unfortunately, the writers also made her a bit of a “damsel in distress on repeat.” She screamed at cavemen, panicked at Daleks, and was constantly twisting her ankle. Seriously, if ankles had a union, hers would’ve gone on strike by the end of season one.
Her tenure ended in The Dalek Invasion of Earth (1964), when the Doctor, in one of his most heartbreaking (and slightly manipulative) speeches, locked her out of the TARDIS so she could stay on Earth with her new boyfriend, David Campbell. She wanted to stay with the Doctor, but he insisted she deserved a chance at her own life — which is beautiful until you realize he basically abandoned a teenager in a post-apocalyptic wasteland with a guy she’d just met. Parenting skills: questionable.
Still, Susan’s role in Doctor Who is monumental. She’s the first companion, the first Gallifreyan besides the Doctor, and the first to prove that life aboard the TARDIS usually ends in tears, heartbreak, or questionable romance choices.