This is a lot, so I won't get all of them, but the Lifeform Analyzer can detect:
Nymphs, bound npc's, The Skeleton Merchant, gold critters, Rainbow Slimes, Paladins, Wyverns, Prismatic Lacewings, Voodoo Demons, Red Devils, Ghosts, The Bride, The Groom, Dr. Bones, Crimson Axes, Corruption...