I was thinking back to my most recent use of these monsters. A fun little exercise.
I have
kept track of most monsters I remember using and encountering.
Black Pudding - Can't remember using or encountering outside of Dungeon of Dread, the first choose your own adventure.
Gelatinous Cube - Used as a DM in my current 5e campaign. A reskinning of a Pathfinder ooze in my 5e conversion Iron Gods adventure path.
Carrion Crawler - I gave my current 5e group a choice of a number of items when they were at a place to trade in a captured magical mace, the kobold bard went for the figurine of carrion crawling.
Mind Flayer - Most recent one I encountered was in a 5e game, it had eaten too many cannibalistic gnoll brains and got mad gnoll disease, which in 5e can be a regional effects issue for a telepath who psionically broadcasts stuff.
Intellect Devourer - Can't remember using or encountering.
Roper - 3.5 I used one with a dark creature and an elemental earth creature template, maybe advanced hit dice. Ambush round grappled and knocked out the paladin with strength damage tentacles. Round 1 died to assault from rest of high level party.
Umber Hulk - 4e faced one when dealing with some neogi.
Mimic - Last one I faced was in Pathfinder 1e doing the Wrath of the Righteous adventure path. I am pretty sure I fell for it.
Rust Monster - I used a bunch of them in my current 5e game as both an encounter (terrorizing the full plate life cleric) and an ongoing plot element as they rescued and allied with a rust monster wrangler ratfolk ranger and recovered and raised a clutch of eggs. I really like the 5e implementation. I am much more sanguine about using them in 5e than in a bunch of past incarnations.
Displacer Beast - I used one in my prior 5e Carrion Crown conversion campaign. The swamper locals called it a cattywumpus.
Beholder - Last one I faced was in 4e. Devolved into a two PC flanking grind slog for the second half of the fight.
Marilith - Last one I faced was in Pathfinder 1e. The most memorable was in 3.5 though, a waitress in a sigil bar. My brother got to use the custom marilith miniature he made with a hooters t-shirt and carrying a tray of wings in one of her hands.
Tarrasque - I have not used or encountered one directly.