Unusually large spiders, fuzzy spiders, daddy-long-legs, centipedes. Ordinary little spiders are okay.
Exposed heights. In other words, inside a tall building is okay, but on the balcony isn't.
Knives. Anything sharper than a dinner knife terrifies me. Not all the time, but usually. Given that I was on the wrong end of one not that long ago, it's a rational fear. I won't be concerned unless I'm still this scared in, say, another six months.
Guns, sort of. I used to be scared even of obviously-toy guns. After working in corrections for a long time, I'm at least comfortable around armed correctional officers and police now.