1. Raxacoricofallapatorian (The Slitheen)
Could it be anything else at number one? When the series came back from the abyss these guys were the most featured new monster to battle the Ninth Doctor, featuring in three episodes of Christopher Ecclestons time in the Tardis. It was probably only when the series aired someone finally said Yeah these things look ridiculous. And they do. They look like massive bug eyed baby dolls. Ugly expressionless baby dolls, that are ugly and not scary. They also look like they have mumps. Ugly non scary expressionless bug eyed baby dolls with mumps. One of the features that make the humanoid beings less human is that they have much longer arms in comparison to humans. Whilst that design choice isnt a sin in itself, it does mean that the actors inside the costumes arent able to use their actual hands inside the hands of the Slitheen. The arms all look limp from the elbows down. Yes, the fingers can bend, but they all look as if each Slitheen has been sitting on their hands until numb, for reasons not worth imagining. So unscary were they, that other then the briefest of cameo in Captain Jacks space age gay bar, they have not been seen in the series since David Tennant took over the blue box. That isnt to say they were banished from our screens forever as they became a regular foe of Sarah Jane Smith in The Sarah Jane Adventures on CBBC. This could well be a result of the BBC having several of the costumes in their wardrobe department, or that they were a familiar baddie from the main series that would also be sure not to give SJA younger viewers any nightmares. All this being said if you came face to face with a Slitheen (or any of the listed monsters) in real life and knew for a fact they real living creatures they would scare the crap out of you! Who knows, maybe real life aliens look like pathetic rubber costumes? Just dont tell them that face to face.