It is striking to me, as an admitted non-expert, that the roots of US protestantism, N. Ireland protestantism, and Scottish protestantism are common in the Calvinist traditions.
The supremacist streak in the former two is well-espoused. Somehow, the Scots get away with a self-image as heroic radicals, but that seems to be to be really no more than better marketing, if one takes the trouble to scratch the surface.