I first saw Jon Gries in Tour of Duty as a guest star. He played the role of a USAF Major who had been shot down and held as a PoW for 3 years. He was very convincing as he portrayed a man who was haunted by his memories of the camp.
When I later saw him playing Broots in the Pretender it didn't click straight away that he was the same guy. I mean the two characters were different. His body language, tone of voice, mannerisms were all completely different. Most actors carry similar mannerisms from character to character, they can't help it they don't even know they have these mannerisms.
In fact it was only when I watched the episode of Tour of Duty again, not long after watching the Pretender that I realised they were the same person. Give this guy more roles!