bystander
noun
[ ˈbʌɪstandə ]
• a person who is present at an event or incident but does not take part.
• "water cannons were turned on marchers and innocent bystanders alike"
Similar:
onlooker,
passer-by,
non-participant,
observer,
spectator,
eyewitness,
witness,
looker-on,
sightseer,
watcher,
viewer,
gaper,
gawper,
rubberneck,
beholder,
