Whether or not character death is on the table depends on the theme of the campaign I'm going for.
If I'm running a zero to hero hexcrawl or dungeon crawl (or both), then it certainly is a possibility, perhaps even a strong one, particularly at lower levels. If I'm running a pulp action serial hero style Eberron campaign or a D&D/supers mash-up, then death is off the table. In the latter case, if you're "dead" by the rules, you're simply taken out of the scene and you're back to once you're conscious again. In some cases, the character will suffer a debuff. In my D&D/supers mash-up, for example, the penalties for being taken out are based on what took you out: 1d4 for a mook; 1d6 for an environmental effect; 1d8 for a villain; 1d10 for a nemesis; and 1d12 for a supervillain. When you roll an attack roll, saving throw, or ability check, you also roll this die and subtract the result. (To remove this penalty, you have to complete a Good Deed, which is basically a minor quest.)