Synonyms for observer

noun

1. One who watches

   watcher, watchman, sentinel, lookout, sentry, guard, detective, policeman, reconnoiterer, spectator, eyewitness, beholder, onlooker, bystander, passer-by, meddler, peeper, voyeur, prying person, peeping Tom*, rubberneck*; see also spy, witness.

2. One who offers original comment

   commentator, novelist, columnist, armchair quarterback*, drugstore cowboy*; see also author 2, historian, writer.