Needless to say, this one has been included on the list purely because Rose Tyler has kept coming back into the Doctor's life like nobody's business. After initially being trapped on that parallel universe forever more, she returned to the series - after a string of cameos - for a three episode stint in 2008 which somewhat diminished the significance of her original exit. After that she made a fleeting appearance in David Tennant's final episode, The End of Time, Part Two, before her most recent involvement during last year's 50th anniversary special. She wasn't technically Rose in The Day of the Doctor, but the point still stands. As such, Rose is widely regarded as the defining companion of the revived series (and some would even say of all time, too, though that's a discussion for a different day) and it's no wonder considering the fact that she quite literally can't stay away. Over the last decade she's appeared in just over 30 episodes and she was the longest serving companion of NuWho before Amy Pond managed to beat her to the post.Perhaps Rose is deserving of the title since she's the one who brought the show back and introduced it to a new generation of fans. Perhaps it's time for her to be laid to rest, too. After all, she's now living her happily ever after with the man of her dreams so there's no reason to bring her back again. Speaking of which...