What are these called for tightening rope wire?
I used the terms "swaged wire rope end fittings" as it's reasonably clear that there's wire rope involved. The crimping on the fitting is called swaging and the rest was up to The Google.

Most of the returns were incorrect. Perhaps the terms aren't the best, but at least one manufacturer used them for their product.



Another term that came from expanding the search is wire rope threaded end or wire rope threaded stud, although that's somewhat redundant.

The images that return from the search show both rotary swaging and bolt-cutter-type swaging and some with none at all, as seen in the drawing above.

I would expect that to enable tightening of the wire rope, one would desire a left-hand thread at one end and a right-hand thread at the other, or else one would have to pre-wind the opposite direction, then insert the stud into the fitting.