Ron Thacker (Jan 16, 1938-Dec 30, 2003, 65 years old) was 19 years old when he participated in the 1957 US Junior Championship and helped Bobby Fischer win the tournament by losing a game to him. Robert Pearson's Blog has an interesting story about Thacker. I notice Mr. Pearson wrote the article in 2007 and was unaware that Thacker had passed away a few years earlier.
Peter Cleghorn (born 1938), a strong master rated around 2400, was originally from California but he moved to Alaska and played very little after that. He played in many of the Lone Pine tournaments of the 1970s and collected wins from a lot of GMs.