I was surfing channels, and saw a few minutes of an old Mannix episode, and the main guest star looked so familiar, but I couldn't place him. It's a Canadian actor named John Colicos.
He played the Klingon commander in the original Star Trek episode "Errand of Mercy".
And apparently beyond that, was very influential on Gene Roddenberry, shaping how the Klingons were developed and portrayed.
On American television, he established himself as a science-fiction villain icon, portraying the first Klingon ever seen in the Star Trek franchise, Commander Kor in the Original Series episode "Errand of Mercy" (1967).[12] Colicos worked with Gene Roddenberry designing the look the Klingons have on Star Trek (1966). Budget constraints prevented the extensive makeup the Klingons were supposed to have so Colicos suggested they have a leathery Genghis Khan look, dark skin and hair.
He also portrayed Lord Baltar in the original Battlestar Galactica movie and television series. Over a quarter-century after his initial appearance in the Star Trek franchise, Colicos reprised his role as the 140-year-old Kor in three episodes of Star Trek: Deep Space Nine, telecast between 1994 and 1998.[13]
I especially got a laugh about this :
Colicos was born in Toronto, Ontario, to a Greek father and a Canadian mother.[2] He was raised in Montreal. He made his acting debut playing Jesus in a Christmas pageant, later joking : "one of the first roles I ever played was the Son of God, and I've been going downhill ever since."[1]