It was the end of an era. Last night, Rose Tyler left Doctor Who. For weeks, since the confirmation that Billie Piper was leaving, the internet had buzzed with speculation about the manner of her departure. Granted, we'll speculate about pretty much anything on the internet (When are the Silurians coming back? Is there a gay agenda behind the Ice Warriors?) but the character of Rose has an appeal that stretches beyond fandom. In all that's been said about Who's triumphant revival, one thing's clear: Everybody Loves Rose.

Well, almost everybody. With her fate shrouded in secrecy, every rumour contradicting the last, and the BBC preview tapes department pretending to be out visiting relatives, anything was possible - life, death, or turning into a big glowing floaty Bad Wolf demigod thing and going off to play with the Eternals (the immortal transdimensional superbeings, not the mid-Nineties girl group). In the end, she ended up in an alternative universe of family life, weeping and Norwegian beaches. The spin-off sitcom, Alternative Lifestyles with the Tylers, can't be far off.

It was a pretty good send-off. The role of the Doctor's companion has too often been an unrewarding one: frequently little more than Dad-attracting eye candy, who spent her time getting captured in daft ways before being jettisoned in strange and terrifying far-flung places (an intergalactic leper colony, E-space, Aberdeen). Not any more; Rose was every bit the Doctor's equal in the buffed-up - and Buffied-up - new Who.

To be sure, she was hardly the first strong female role in sci-fi or fantasy - Russell T Davies is open in his admiration for Joss Whedon, whose work on Buffy, Angel and Firefly gave us more strong women than you could shake a stake at. But in tackling a role so often stereotyped as the ultimate ineffectual woman, Billie reinvented what female characters could do in this most boy-dominated of genres.

Not only did the character of Rose remove any trace of the little lady from the Doctor's companion, she was also unashamedly working class. But she never played to the easy television stereotypes: that if you live on a council estate you must either be gritty and miserable or outrageous comic relief. She was just an ordinary teenage shopgirl, doing what most teenage shopgirls would do if whisked off by a 900-year-old alien in a magic, time-travelling blue box.

That these elements - potentially jarring and inappropriate - were handled with such a convincing light touch was a tribute not just to Billie's acting, but to the writing of Davies (and the peerless Steven Moffat, who gave Rose her iconic moment - in a Union flag T-shirt, slow dancing to Glenn Miller on a spaceship tethered to Big Ben in the Blitz.)

But it was never a certainty that Rose would be taken to the nation's hearts. When news of Billie's casting broke, it was greeted in certain quarters of fandom with howls of outrage. The idea of some teenybopper best known for a slightly unsettling marriage to an older DJ defiling Doctor Who was too much to take.

Dark predictions abounded that the series would be swamped by inappropriate musical numbers, and tabloid headlines shouted about romping with Daleks. Some were even moved to commit the ultimate heresy - they wished Bonnie Langford would come back.

Instead, Rose was an instant winner, loved by fan and casual viewer alike. She's changed the way female characters are seen, working-class characters are seen, and genocidal metal pepperpots from the Planet Skaro are seen. So goodbye, Rose. You were fantastic. We wish you the best of luck in your new career.