The abomination in Ghostlands when I was a wee Blood Elf with no heirlooms a long time ago.
The human farmers that used to be in western Tirisfal Glades pre-Cata. They would run away at like 40% hp and come back with ten more.
Cheerful lack of self-preservation
Was a young paladin in vanilla, wandering ouest of elwynn forest "Oh a bridge, lets see what's on the other side". That's when I encountered the most evil creatures of all Azeroth : the mechanical harvesters !!!!!
Those level 14 (if I remember right) where way too hard for my not even 10 paladin. I ran for my life back into elwynn forest.
One of my first characters ever made, it was a tauren shaman. I leveled in Mulgore till level 12, mostly around Bloodhoof village. But then one evening I was chatting with other players near the bonfire, and one of them told me I should go to the other zone at this level. I listened to him and went to Barrens...but I did not stop at the Crossroads. I dont know why but I went further, into Ratchet and then on a boat...
Imagine my eyes when I got to STV for the first time, all ?? level mobs and alliance players!! around. I was pretty shocked. I think I was killed right at the exit of booty bay by some Gorilla or Tiger.
I was just in Duskwood on my level 30 void elf, and someone is about to die to 3 marauders. So being a nice person, I start firing at the mobs to help him out, and then realize these mobs are Skull level to me and I'm like oh crap someone is doing their Artifact quest out here ... and the other player dies, and so then I die horribly.
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Teremus the Devourer killed me who knows how many times. He patrolled the entirety of the Blasted Lands during Vanilla, a big black dragon, but he didn't make any noise until aggro'd. So he'd sneak up behind me while I was questing or grinding out there and murder me super fast. One time my friend Lou kited him all the way from Blasted Lands to Stormwind haha ... his account was suspended for like 3 days for doing it. Anyway, I named my fire mage Teremus after him.
Stitches in Duskwood.
Devilsaur in Un'goro.
Fel Reaver in Hellfire Peninsula.
"That dragon whelpling seems like a foe I can vanquish" - in Redridge mountains when I started playing wow
Proceed to get obliterated by it...
Gues you should'n go for an adventure to Redridge Mountains at lvl 4 ( and setting a hearthstone destination there)
That rare yeti mob in Dun Morogh - well this was 10+ years ago now and I back pedalled and used hunter melee skills....