The first three are different actors but are understood to be the same person, the 4th is because of a bigger budget and perhaps Starfleet spent more on ships in the alt. timeline because of Nero's attack, the 5th one makes no sense at all and the last one is because the Kahless that Kirk etc. saw was his idea of what he would have looked like, not what Kahless actually did look like.
It took 40 years to explain why the Movie/TNG+ Klingons looked different than the TOS ones. And there's never been an explanation as to why there are so many variations of Movie/TNG+ Klingons. So, why does this variation need an explanation?