major character is shot w weird space gun that steals his lungs: doctor devises a set of holographic lungs to keep him alive until adequate replacements can be found
minor character gets stabbed once in the back w a regular old knife not 50 meters from sickbay: dies instantly. bashir scans him w a tricorder and shakes his head solemnly. there’s nothing he can do.
major character suffers traumatic brain injury, rendering him comatose and just days from death: doctor grows a genetic clone from a gob of alien goo and harvests neurological tissue at just the right time (not w/o its moral dilemmas)
tasha yar zapped by a tar pit: beverly crusher