The first Klingon is not Saxon but John Colicos who was also Baltar on the original Battlestar Galactica.
The Kreeg were brutal, thuggish mutants who had ridged foreheads, I wasn’t referring to Saxon. The last pic shows the transition from Colicos to John Quade (as the Kreeg commandant) to Mark Lenard in ST: TMP as the full timeline of what Roddenberry was trying to do with the cranial ridges physically. They got almost comical in ST: III (they looked like they got a reverse bowl haircut while being hazed by a Boy Scout troop at summer camp), but once Next Gen hit the screen, they had the system down, the budget to do it, and took it all over the place. The Klingons in the J.J. Trek movies and Star Trek Discovery look like the designers were dropping acid when they started playing with the accepted look.