I've met three, Herd, Swingle and Lett. Herd was our DO and he was a dynamic speaker.
Met Swingle through his sister who was in our congregation. His sister was very quirky, she just did what she pleased and never asked permission or apologized. (I related with her very well) As I recall the elders tried to steer clear of counseling her because she intimidated them. She and her brother both were fun drinkers.
Interesting story about Lett, Sr. In that congregation my father in law, an elder, became involved in a dispute about building a new hall. Lett, Sr moved in right in the middle and he sided with all the other elders against us. In the end, the whole family and our book study were embroiled in it. When my mother in law and I would go out in service no-one would speak to us and when they made up car groups we were totally ignored, left on our own. There was a special committee set up and I remember sitting in on one meeting with them. My mother in law was talking about the hurt she felt at being treated badly by people she had been close to for 20 years, and she broke down crying (I had never seen her come close to tears before). The elder in charge of the special committee sat right there and accused her of grandstanding, of faking it. We were in absolute shock.
At any rate, the CO threatened to padlock the door, and while he had great sympathy for us he advised us to move to another congregation because these people made it clear they had no intention of ever accepting us again. So we did, but about a year later, Lett Sr came to see me at my place of work and actually wanted to apologize for his part in the dispute, saying he didn't do enough to get all the facts before taking sides. Then he gave his real reason for coming to me, he wanted me to convey his apologies to my father in law! He wasn't man enough to apologize in person, so he came to someone who was a lowly female, someone who wasn't important enough to make him feel shame. I wonder how that type of attitude influenced his son, hmm? Also, when I met Jr. he seemed to be pretty strange.