My worst crash was caused by a pedestrian. Pedestrians entering the roadway without looking because they don't hear an engine coming are a constant hazard to urban cyclists, because they're totally unpredictable. (I expect that most hearing-impaired pedestrians actually do look both ways, and thus are less of a threat.)
My worst near-misses were caused by wrong-way cyclists. One coming around a blind corner; the other coming at me on a fast 4-lane highway with no shoulder.
I fear pedestrians and ignorant cyclists much more than I fear motor vehicles.
RichC