Here's a tricky one. Even though he was active with the Five-0 team both before and behind the camera, we really came to "know" him in only one episode.
Right you are, Honu! In addition to playing the "fake McGarrett" in Season 7's "Welcome to Our Branch Office," he also served as Jack's stunt double and as a lighting technician.
Okay, is it Thorwald Boie?
He looks a bit like Joseph Sirola, but I don't think it's he. I'll keep thinking.
This is a shot in the dark: Beau van den Ecker?????