I'm horribly afraid of heights and can't even stomach a normal wall climb (like with a harness and everything) without quivering like a leaf.

Also most BIG bugs, especially if they have a lot of legs... though I think I'd probably be fine with a tarantula, for some reason. No idea why. The small ones are usually fine, minus wasps and hornets.

I'm kind of afraid of the dark too, but it's also not really about the darkness itself. I'll find myself vividly envisioning things like a snarling wolf suddenly lunging from the darkness to tear my throat out, or a large, unhinged man sneaking up behind me, or some shit like that. It usually only happens outdoors in rural areas where nights are much darker, which allows my imagination to run more wildly than usual. Thankfully, I live in a city now.