That's now four main cast member deaths for a show that started in 1993. B5 must be fast approaching some sort of unfortunate record of premature deaths.
You're not the only one who thinks that way. From FB:
Fans of J. Michael Straczynski wrote:
Richard Biggs. Andreas Katsulas. Jeff Conaway. Tim Choate. Michael O'Hare. Enough already. Go pick on somebody else's cast.
I never met Michael O'Hare but very much admired his work on B5.