Doctor Who: 10 Cheapest NuWho Enemies

Sometimes an actor's face can say more than a platoon of Cybermen invading a major city ever could. This principle was employed to great effect in Boom Town, a two hander of sorts (well, a hand and a Slitheen claw at any rate) and an unexpected sequel to Series 1's Aliens of London/World War Three two-parter. 

Re-using the gangly outfit from the earlier story and promoting Annette Badland's Margaret Blaine to the fore, the script took Doctor Who into more intimate territory for the first time, giving viewers a character study more than a rollicking slice of sci-fi action. A restaurant rather than a starscape became the centrepiece of the narrative, which like the previous entry filled a gap created by a departing writer (in this case Paul Abbott).

Of course, the fact that the episode saved the series some urgently-required loot in the run up to Dalek-heavy extravaganza Bad Wolf/The Parting of The Ways was a happy coincidence. So as Badland surfed her way to freedom on a cosmic wave, the BBC accountants slept soundly that night.