A lot of us remember him best from "LA Law", where he was very effective as the senior attorney who was something of a father-figure to the firm's headstrong gang of trial-lawyers. It was a good show, and he made it better.
I remember Dysart mostly as the only actor I don't associate with his role in Columbo as much as the character he played in "Being There" who saw Chance (Peter Sellers) for who he actually was.