This question What is the earliest published horror anthology of original material? asks what was the earliest horror anthology of original stories, published for the first time in the anthology.

So what was the earliest horror anthology of reprinted stories which were first printed in some other book or magazine?

Obviously the first horror anthology of all must be at least as early as the first horror anthology of original stories, while the first horror anthology of reprinted stories might have been before or after the first horror anthology of original stories.

The earliest Horror Anthology of original stories suggested in the answers to that question (as of midnight March 2/3 2024) is August Derleth's Dark Mind, Dark Heart (1962,1966).

Which gives a latest possible date for the earliest Horror Anthology.