Charlotte "Charley with a y not Charlie with an I she was forcibly evicted for damaging a camera" Pollard is a companion of the Eighth Doctor originally, later on joining the Pie Doctor. Originally from 1930, the Eighth Doctor rescued her from dying on the R101 where she was hanging out as a reverse trap. By rescuing her, the Doctor fucked up time so much that it would eventually make Zagreus happen, the greatest let down in the universe. After her travels with Sixie, she gets her own series of Dick Fisher ear stories where she runs away from a bunch of Stormtroopers who create diseases after being their emissary or something.
Charley was an "Edwardian Adventuress," which is a fancy way of saying she didn't need no man. She ran away from home to become sexually liberated with some guy she met at a party one time, but ended up meeting the Doctor and becoming a pretty cool chick.
She can still be a bit of a brat at times, but has lots of good points that more than make up for it. Her and the Doctor are one of the best examples of the companion being best friends to the Doctor without making it all lovey dovey. Well, until Scherzo.