Slitheen. The "v" is an artifact of Rose's accent. :P

I can spoil you for next season's casting without giving away plot details, if you're interested.

I thought 10 was a great episode, but a lot of old skool fans hated it because it was effectively an ode to Doctor Who fandom, and they felt like they were being sent up. The Kennedy-like fans, that is, who frankly deserve sending up.