9. Beetlejuice (Say His Name 3 Times)
Beetlejuice, although more a figure of comedy, is an undead being of incredible power whose job as a "bio-exorcist" is to scare the living out of houses (and Beetlejuice was a horror-comedy, so he does fit the bill for this list). In order to call upon Beetlejuice, all you have to do is say his name three times; "Beetlejuice, Beetlejuice, Beetlejuice". Upon his arrival, he is generally soon sussed out as a very, very annoying individual, so the first instinct of anyone who calls him should really be to get rid of him immediately. If you want to do that, all you have to do, at any time, is say his name again three times; "Beetlejuice, Beetlejuice, Beetlejuice". And he's gone. He might try to stop you, but if you catch him out and say it fast enough, you really should get rid of him without any major issues. Easy.