watcher
noun
[ ˈwɒtʃə ]
• a person who observes something attentively or regularly.
• "a badger-watcher"
Similar:
onlooker,
spectator,
observer,
viewer,
looker-on,
witness,
eyewitness,
fly on the wall,
sightseer,
bystander,
passer-by,
non-participant,
spy,
rubberneck,
beholder,
