7 or 8 TPKs as a payer or DM since the 70s. A few more games that just ...faded to a stop. We stopped playing those PCs, but continued (later) with the same DM in the same world.
A few times we just ended the campaign after a TPK. In some, we picked up the tory a 'generation' later with the world feeling the pain of the first party's failure. In others, the world was left behind.
In one game I ran, I told the players not to make new PCs (sometimes people get excited about starting a new character and it is a disappointment when they return to the PC they've played for so long). Then I handed them character sheets for friendly NPCs at the start of next session and gave the PCs a chance to save their fallen PCs... as their friends... but doing so came at a cost to those NPCs, but they'd all be willing to pay the price. For most of the players, the pain that bringing them back caused to the NPCs was a motvational tool that made the game more intense.
In one game I played in the entire party was turned to stone. They were revived a thousand years later, in a world that had changed dramatically around them. It didn't really work as well as the DM hoped, so he retconned in a time travel element to effectively undue it.
One game had an adventure in that world's Limbo plane, where souls waited to be claimed. This allowed them to return to the mortal plane in other bodies.... It was fine, but we were close to the end and we rushed through it as we didn't like the twist so much, even though I ended up with a paladin in a giant ape's body.