If you got Rose Tyler on a bacon slicer (and I encourage everyone in the Whoniverse to give this a go) and sliced her into wafffer thin slices, you'd find the name Mary Sue written through her in Old High Gallifreyan.
Turn away if you haven't got to the end of season four dear reader.
Rose Tyler (Rose a now not common name in area she resides, Tyler an author signature name...it appears in almost every project RTD has written for) AKA Bad Wolf (a universally recognised meme across the whole of space time which the Doctor doesn't know about).
A gymnast at school, described as attractive enough to be a wife, concubine or prostitute. Almost everyone falls for her charms other than the Doctor (joke).
Born in relative poverty and obscurity is actually the heir to a large fortune but not in the same universe but by pure fluke (or divine self intervention) ends up being in the universe with the millionaire version of dad so she can benefit from it in her future and go from shop assistant to planetary defender and learn how to hop dimensions even though this has been clearly stated to be really dangerous to all universes concerned not to mention impossible.
She has mega lapses in empathy (Mickey definitely but seems more concerned with getting Queen Victoria to say "We are not amused" than all the people dying around her to the point that this actually has to be pointed out by said monarch) this has a knock on effect with the Doctor who has this trait on occasion but usually it's an act, after being around Rose it becomes practically a way of life.
She became a God to save the idealised projection of her absent father (The Ninth Doctor) after failing to save her real father despite almost killing everyone on Earth including the Doctor in the attempt (but she gets the real one back anyway with the added benefits of gaining a fortune and giving her mum her lost love back but with all those troublesome edges knocked off).
He transforms into an idealised projection of the best boyfriend ever (the Tenth Doctor) and she enters a doomed 'platonic or isn't it?' (no it isn't) shipsaga but it's ok because she gets to have her man and not have him via a handy clone (her long suffering boyfriend despite character arcing from zero to hero conveniently jumps out of the way at this point).
She dies a romantic death only she doesn't and the Doctor, Martha and the audience has to suffer his constant moping until she returns so he can die in her arms (only he doesn't).
Need I go on?
As re-jigged from 2005 onwards the Doctor himself is pretty much Doctor Sue too.