I believe everything has the capacity to reflect some light except a black hole, which is able to trap that too[1].
But as far as the human eye can detect, there are probably a lot of things (whether real or artificial) that are indistinguishable from this 'true black'.
[1] Black holes can trap light outside the visible range; I'm not sure if there's something that can trap the entire visible range but not everything outside it.
But as far as the human eye can detect, there are probably a lot of things (whether real or artificial) that are indistinguishable from this 'true black'.
[1] Black holes can trap light outside the visible range; I'm not sure if there's something that can trap the entire visible range but not everything outside it.