RIP, though I have to say his acting performances in DS9 and B5 were underplayed to the point where he might have been better off playing a Vulcan. I assume he was more lively in other roles, but maybe that was just his style and he was miscast?
FYI - Here's a link to an article in the Hollywood Reporter about his passing: http://www.hollywoodreporter.com/news/bernie-casey-dead-actor-nfl-910749
He was also memorable as the chief gargoyle in the 1972 made-for-TV creature feature Gargoyles, even though his electronically distorted voice was dubbed by Vic Perrin.