Captain Crazy Chicken
The bad guys are pirates?
For me, I'd have to say 0 and 02, though I rather enjoy them. Scary, but fun! Which bosses have scared YOU out of your wits?
Any of the Silent Hill bosses. They used to scare the crap out of me when I was younger.
Ornstein and Smough from the first Dark Souls, but that was more because I'd been told that they were super-hard, even for DS bosses. Once I got the hang of fighting them, they weren't so bad. I actually spent a while farming them for souls and helping other people get past them.