Here is an uncomfortable sentence.
Your HSA is the only account you own that can literally stop existing the moment you die.
Not transfer. Not convert. Not roll over into something with a different name. Cease to be an HSA, on that date, with the entire balance converting into taxable income for somebody.
Or it survives completely intact, keeps every tax advantage it ever had, and quietly continues for another thirty years.
Which one happens is determined by a single field on a form you probably filled out during benefits enrollment years ago and have not looked at since.
That is a wild amount of consequence riding on one line of paperwork, and almost nobody checks it.
So let's go through every scenario. Spouse, adult child, trust, charity, nobody named at all. What the tax bill looks like in each case, what the beneficiary has to do, and the one deadline that can save a lot of money if someone knows about it in time.