Some random former core monsters that have stuck with me:
Floating eye (1E Monster Manual)
These are (probably) based on Namor's
hypno-fish from some old Marvel comics, and I suspect that's where my affection for these oddballs came from.
Wereshark (D&D Rules Cyclopedia)
They seem like the logical oceanic counterpart of werewolves, but they haven't made an appearance since 3e. I could easily see sahuagin weresharks being a thing...
Crypt thing (Monstrous Manual)
The idea of a neutral, rather than evil, undead guardian has an unexplainable appeal to me. I updated them for one of my 5E games, as the guardian of an ancient tower that rose from the ocean. When the party caused the tower to collapse for good, I had it teleport itself so it could intercept them while they fled...
Deepspawn (Monstrous Manual)
A monster which completely justifies the classic, randomly generated dungeon crawl. What's not to like?
Brown dragon (Monstrous Manual)
I was disappointed these flightless desert dragons didn't make a comeback in Fizban's. It never came up in our last campaign, but I assumed rogue brown dragons lived in the deserts near our setting's dragon-ruled kingdom of Vemurion.
Eyewing (Monstrous Manual)
Another monster likely among old favorites because it reminds me of a monster from other media: the
fire eye from Castlevania III.
Wemic (Monstrous Manual)
A player in my first D&D campaign created a wemic PC, so there's some nostalgia wrapped up in this choice. They've consistently been one of my top picks for a 5E return, as a monster or as a PC option.
Primordial naga (4E Monster Manual)
Most of 4E's monsters left me cold, due to the lack of lore, but the concept and mechanics won me over on this one, with all those different elemental attacks. A 5E return as a mythic monster would be neat.
