How do you deal with PC death? 

Do you avoid it and handwave the dying so the PC is only unconscious but scarred or has a lasting injury?

Give the party a "lucky" res scroll or nearby temple?

Let the party figure it out themselves?

Laugh like maniac and shout next!

What about a TPK?

I've only had (knock on wood) one TPK. But I gave the party a chance. I texted each player and said a "mysterious voice" asked if they wanted to live. One of them said no - they wanted to stay dead. The rest of them chose to live and were told there was a cost for life. Without telling them, I lowered their level by one and gave them a level in another class - The Paladin and Ranger got a level in Fighter and the Sorcerer got a level in Rogue. Do you think this was fair? 

Currently playing CoS, so i have warned players that death is a possibility. To this end I’ll hand wave some components but if the party want to res their characters they need a 300gp diamond. Only had one player death and it was party their choice, they wanted to try something new. It’s really difficult to actually kill characters with spells like healing word. I wouldn’t hand wave it though, if the player wanted to continue their character then I’d craft a quest to find a mcguffin/ scroll to resurrect their character and let them use a temp character.

I have spoken to my players on a rolling session zero to see what their desires are on their characters if they were to die, and presented them with options. One has said they would prefer that they died and he would start another. Others have said that they would be interested in some form of after-life questing or deal with death. 

I have not yet planned for consequences - something I really need to do as the campaign is escalating from "local heroes" to "Taking on a giant kingdom led by an invincible king" at a startlingly rapid pace!

Giving them a class, I would avoid, especially as I want my campaign to go up to level 20, so that would scupper their planned development. However, I would absolutely curse them!

I feel like it would be a good one to have a character die, and they hear a voice whisper "I can get us out of this, but you'll have to trust me...". If they agree, they will wake up somewhere else, later on, covered in blood and surrounded by devastation - turns out they've Werewolf blood in their veins, which manifested to keep itself alive - and now they're a Werewolf.

I would aim for roleplay stuff. EG, they wake up, but they have lost all memories of the party. Or they wake up, and have a Patron like a warlock, who instructs them to do stuff and threatens them with death if they refuse. I would also make these things they can reverse with proper questing!

Well, um...

Play in my games, and you have a good chance of dying. A higher chance than default rules.

There are temples and shrines all over the place -- but they only work for folks who have been baptized (and players can choose three of them). So resurrection is possible (ain't cheap, but possible).  There is a time limit. You cannot resurrect a 200 year old dead person in my game -- usually, it's 7 days (raise dead), 49 days (Resurrection). 15 years if you use reincarnate, but the longer the time, the greater the risk to the sanity of the reincarnated. Most folks cannot afford to bring the dead back. Only the wealthiest (high level Gentry, Patrons, Nobility). ANd since worship of the Powers is uncommon among the wealthy folks, they don't usually get it.

So, that's the mechanics of it.

We are a roleplay heavy style group. I love it. We've had several sessions that are nothing but RP, and we really get into our characters, so death is a huge thing for us. the higher the level, the more pronounced because there's more time invested (years, literally, at higher levels). That makes death painful for us as people.

And I really, really dislike the hurt stuff (I have personal issues with grief). So there can be a lot of emotion involved. 

Because death is a high possibility, there is always a "backup" character. I don't put any requirements on them, and some folks just make them a copy of the original. We create the main and backup at the same time, and then go for the campaign. If both die, well, then they have to create a new character -- and honestly, there are usually a few sessions where they don't come back to play.  They have to process the grief of a beloved character.

The one exception has been when they chose to sacrifice themselves for others, when they opted to do the big hero thing. Which I built an entire campaign around, but I never make that a thing where I put them into a situation on purpose they have to do it normally.

I give them all the death saves and all the normal stuff to hang around -- which is a huge change for us and has been for like a decade now -- we always used the "0 equal dead" HP thing.

But we also kicked out double damage crits, so the usual normal stuff is what we deal with.

I have active Powers (gods). THey are present, persistent, around. You might encounter them walking down a road or running a tavern or sitting in a nice little home in the middle of nowhere. Cleric types may be told "you have to have this spell" suddenly, and have it pushed into their slots, wiping out one (like a spell for making split pea soup -- and then later that day they will meet a beggar who hasn't eaten in a while and happens to like split pea soup.). One can ask for a Trial by Ordeal -- and the Powers will protect them if they are innocent (or at east in great favor at that moment).

So they can pray. If not baptized, they may still be heard, but then they have to make a bargain. It's built into the world, so it isn't me just doing something to save them -- it's a valid and real thing.

So there are in-game ways to deal with dying. THere are also in game risks to it -- fail to deal with the corpse after a bit, and it could rise as an undead -- and not under the Player's control.

Out of game, it is always about how attached to the character the player is, and I am usually willing to do something if they just don't want to switch to backup -- the goal is to have fun.

But this isn't a video game. Death is a consequence and I keep it there as an underlying theme of things -- the heroes do not always win; it is up to them to make the wise choices.

As a DM i honor the dead so if a character dies, so be it. There's always the possibility to be restored with high magic but it's usually rare and costly so most just roll up new one.

I use something similar to Mercer's rules. If the player character dies (s)he can be revivified within one minute. After that, Raise Dead can be used but a d20 is rolled and if the number isn't at least 8 the player character remains dead. This DC increases by 2 every time the PC is successfully resurrected. Other player characters can attempt to lower the DC by 1 up to three times with successful ability checks to call out to the soul wandering towards their afterlife. 

A revisit of the OP makes me realize I skipped out on something: TPK.

Total Party Kills are a thing I do not normally have to think about, but I have to admit that they can happen.

For me, they usually happen when they are still low level, and not quite into the 4th level if they do happen, and because I don't ever set things up to happen a certain way (winging it) I am usually able to avoid a TPK -- which is usually signaled by one death. At that point, I can see where things are going to go after that, and usually a few ways to step around it.

That, however, is not a skill I think I can teach, even through direct examples. Nor fully explain, as it is part of how I see the real world, as well. 

Some of this leans into the way I plan my adventures, though. Because I outline possible events (me thinking as a player and what they might do) and the probable outcomes, when they inevitably try something I did not think of, I have the ability to adapt and flex my scenario by combining elements of what I have thought of, which fits into my play style.

So for the most part, I am able to avoid them as a result of something on my end -- but that does not preclude something on their end.

One of the things about creating a world where Death is supposed to be a real thing that can happen traveling in 'safe lands" between a nearby town and a village is that you have to have potential problems that are capable of killing things that can show up randomly. While a standard 5e Commoner stat block may be what many use, I don't have that luxury -- essentially, my commoners can be anything from that to something much more -- 20 hit points, AC 13, average damage of 3.5. So my creatures are capable, at a base of doing such harm to people. That's assuming a basic farmer whose been doing his farming for a while and is really really good at farming -- think of it in terms of class to a bit.

And that is the "safe" areas -- functionally within 15 to 30 miles of a settlement (about the range of a patrol, with the shorter the norm and the longer based on their having a station of place to rest horses, etc). The unsafe areas can be much, much worse -- and in some cases the random encounter may be more than they can take on.

That places the party in the situation that some have noted in general -- do they stand and fight knowing they will die, or do they run. Or do they negotiate? Or do they go tactical? These are the situations I have the most worry about it -- because this is the nature of the setting, the world in which these heroes are supposed to be active, supposed to be heroic in.

And if they choose to face the monster, there is only so much I can fudge HP and damage rolls before it becomes obvious I am doing so, and that takes some of the joy of victory against an unwinnable foe that really drives those moments in my game. ANd I encourage those kinds of things through generous use of Hero, Inspiration, and related points (they are called Destiny Scores, collectively, after all, in my write up -- because they allow the Players to change rolls, change outcomes, and change destiny, which is wholly represented by the funny little math rocks).

While this is most common at lower levels, it can happen at higher levels, as well. The risk is lower in these kinds of circumstances -- but not negligible, and still probable if they are following a plot thread or choose to do something genuinely foolish like jump into the Crusades.(another thread asked about doing battles and I explained my approach for how that works elsewhere -- but note that as part of creating this world, I had to anticipate that someone might want to do that and figure out how).

The big key is that it is really hard to blame me for killing their character when they made the decisions. I don't set out to kill characters, but I do set out to challenge them right at the point where they could die.

So, that's what I have for that.

As DM i honor the deads and if a TPK occur, so be it. I'm not one to undo stuff just for the sake of it, when a campaign ends we jumpstart another.

Past level 1 badluck, i rarely have TPK though,  as the difficulty of most encounters i run are medium to hard, few easy or deadly one and always encourage a party to explore other options than only fight-to-death, like parlay or flee.