7. The Slitheen In "Boom Town"
In their previous appearance in "Aliens of London/World War Three", the Slitheen had managed to infiltrate the British Government and advanced their sinister agenda, before being thwarted by the Doctor (of course). By the time of this adventure, just one Slitheen, Blon Fel Fotch, has managed to survive. She spends most of this episode pathetically begging to the Doctor to spare her life in a hoity-toity restaurant, which Christopher Eccleston seems very bemused by. Unfortunately for her, this Doctor no longer feels any mercy for her (or most things, really), and refuses to spare her life. He does, however, helpfully offer her breath spray. It's an interesting reversal of the usual Doctor Who formula, with the Doctor having all the power and control in the situation and refusing to help. The Doctor does come off as somewhat of a hardass here with his usual post-Time War crankiness, but the reason this episode doesn't ultimately work in a satisfying fashion is that at no time do we ever feel threatened by Fotch. The Doctor clearly holds all the cards in this battle from the outset. There's not much to speak off in the way of suspense here either, despite Fotch's attempt to hold Rose hostage. We need stakes for effective drama, and this just looks like the Doctor picking on a defenseless enemy, which is not in the spirit of Doctor Who.