Yep, the actors who played G'Kar (Lung Cancer), the Doctor (Aortic dissection), and now Zach (Drug issues and Sepsis) have all passed away, all being title characters.
Also, the actor who played Dr. Franklin dad died of a heart attack in his 60s, The Pilot doctor died (but he was in bad health at the time of the pilot) and the actor who played Zathras died in a motorcycle accident. Rather depressing, Heck, even TNG has all its main cast and most of there guest stars still alive (except the ones who where old at the time and Merritt Butrick who died young due to AIDS. )