'nightcrawler' originates from English, a compound of the words 'night' and 'crawler', where 'night' meant 'night' and 'crawl' (from Old English 'crāwlian') meant 'to creep or move close to the ground'.

'nightcrawler' is attested in American English from the mid‑19th century primarily to name large nocturnal earthworms used as bait; 'crawl' developed from Old English 'crāwlian' through Middle English into modern 'crawl', and combined with 'night' to form the compound 'nightcrawler'.

Initially, it meant 'a worm that crawls at night (used as bait)'; over time the sense extended metaphorically to mean 'a person active at night' and later was adopted as a proper name for the comic‑book character.