Doctor Who: 30 NuWho Characters Who Would've Made Fantastic Full-Time Companions

Appeared in: Under the Lake/Before the Flood.

We owe a massive debt of gratitude to Moran (Colin McFarlane) for heroically saving Cass' life right at the start, thus continuing one of film/TV's traditions of having a well-known actor snuff it early on in the story.

Writer Toby Whithouse's brief character description of her in the shooting script is: Cass - Female. Military. Second in command. Deaf, communicates through Lunn. Brave, disciplined. Then add to that the Doctor's compliment: "Whenever I step outside, you're the smartest person in the room."

Cass demonstrates these attributes marvellously - and shows that her deafness is no barrier - during that anxiety-inducing scene in which she evades ghostly Moran's swinging strike of an axe just in the nick of time. It's your classic apparition about-turn.

You'd have to bring the loveable Lunn along too, given how the Doctor's sign language skills have been deleted. Probably due to those sonic sunglasses deleting more than just his browser history. Oh and the fact that Cass and Lunn are madly in love with each other.