I LOVE Nethack. I never ascended, the most far I got was The Quest level of Valkyrie, usually I have no problems finishing Gnomish Mines & Sokoban, but then things get tricky.
In old Amiga days I was playing some other rogue games, like Larn, Moria, ADOM, Angband, and Zangband, but Nethack is the best IMO.
There's an incredible tileset for Nethack -
Absurd.
Also,
spoilers are a must.
Hmmm, my most Yet Another Stupid Death (YASD) was when I was wielding cockatrice corpse (you can instantly petrify enemies with it), in gloves of course, but I was burdened so when I tried to walk down the stairs to next level, this is what happened:
You fall down the stairs.
You touched cockatrice corpse.
You die.

There was one more YASD - my pet (tame dog or cat) stepped onto a polymorphing trap and changed into Arch-Lich (one of the most powerfull creatures in the game). That was great, through many levels my Arch-Lich was instantly killing all the nasties (including Shopkeepers

) and I was on a good way to ascend with such a pet, but then Umber Hulk showed up. I was so self confident that I didn't check in the spoilers what kind of creature an Umber Hulk is. Now I know that it's a relatively weak creature, but its attacks are confusing, so when my Arch-Lich attacked Umber Hulk, he got confused (confused pets may attack their owners), and on the very next turn my confused Arch-Lich has cast a Death or Disintegrate spell on me. Oh well.