In all of their appearances that I can think of in the TV shows, I can't remember having seen a single Klingon individual whose ethnicity differs much from the dark-skinned "standard" one that we are accustomed to see:
Even other alien species could have different ethnicities (one of the main examples is Tuvok, a dark-skinned Vulcan), so we know that Humans are not the sole species to possess this kind of feature.
Do light-skinned Klingons exist? Do different ethnicities exist within their species as a whole?
For the sake of simplicity, this question refers to anything released before Star Trek: Discovery, where the Klingon, like almost everything else in the series, were depicted in a very different look than before, AFAIK without much explanation other than out-of-universe production choices.