As we trundle along, merrily throwing alien after alien at the hapless human intruders, it's always nice to pause and add a little sumpin sumpin to the lists of the fantasy dungeon. Why not some twin manticores to spice things up?
DN58 - Manticore
These ugly mugs can be found in Pendraken's Dungeon Monster line.
They aren't that big compared to the humans, but with that uncanny valley face, they're still pretty intimidating.