This week we'll continue with the creepier side of etymology. Last week we did (un)dead creatures, so let's see about some live ones for this week.
Demon, from Latin daemon, "spirit," from Greek daimon "deity, divine power, lesser/guiding spirit" from Proto Indo-European root da- "to divide," as in divider of destinies. The "god of the heathens" or "unclean spirit" meaning gave root to a fun synonym in Old English: hellcniht, "hell-knight."
Werewolf, from Old Englis werewulf, from wer "man, male person" and wulf "wolf." In a similar vein we have Middle Dutch weerwolf, Old High German werwolf, and the Swedish varulf. Fun fact: in the ancient Persian calendar, the eighth month (October-November) was called Varkazana, Month of the Wolf-Men.
Witch we've done before, but what about warlock? It's from Old English wærloga, "traitor, liar, enemy, devil," from wær "faith, fidelity, a compact" and the second element is related to leogan, to lie. The original meaning seems to have been "oath-breaker," which was used of giants and cannibals also. The "in league with the devil" meaning is only from the 1300s. The "male equivalent of witch" thing is from Scotland in the 1560s.
Creature of course comes from Latin creatura "thing created," but it doesn't say by whom. On a related note, the word monster comes from Old French monstre, "monster, monstrosity" and directly from Latin monstrum "divine omen, portent, sign; abormal shape, monster, monstrosity," figuratively "repulsive character, object of dread, awful deed, abomination," from root monere "to warn. " The omen thing might seem strange, but you have to remember that at the time abnormal animals were regarded as portents of evil. The meaning was extended to imaginary animals like griffins etc. in 14th century. Remember Grendel from Beowulf? He was called an aglæca, a word related to aglæc "calamity, terror, distress, oppression."
Not a creature, but let's do jack-o-lantern as a bonus. It's from the 1660s, a local name for the will-o-the-wisp, Latin igneous fatuus, "foolish fire." The carved pumpkin thing only added 1834 by the American English.
Have a creepy and glorious Halloween!