Most Trekkies would know him as Commodore Matt Decker from the one Star Trek (the orignal series) episode called The Doomsday Machine.
The easy-going Windom was an in-demand television character actor for decades and scored guest appearances on several American TV staples, including episodes of Twilight Zone and Star Trek and appeared on more than 50 segments of Murder, She Wrote beginning in the mid-1980s.
Not mentioned in the above-web-link but he also had a role (as Charlie Snead) in the 1971 TV-made movie The Homecoming: A Christmas Story that launched The Waltons TV series a year later.
His entire filmography is on the below-link:
He certainly was in a lot of movies and TV shows.
[Edited 2012-08-22 15:04:17]