Argus
Charley
TV-viewer
airplane spotter
beholder
bird-watcher
bystander
crown
dragon
dragoness
drugstore cowboy
eyewitness
fire patrolman
fire warden
fireguard
forward observer
gaper
gazer
gazer-on
girl-watcher
goggler
guard
invigilator
kibitzer
looker
looker-on
lookout
lookout man
night watchman
observer
ogler
onlooker
patrol
patroller
patrolman
perceiver
percipient
picket
roundsman
scout
seer
sentinel
sentry
sidewalk superintendent
spectator
spectatress
individual
mortal
person
somebody
someone
soul
correspondent
fisherman
follower
guardian
horseman
hunter
intruder
listener
on-looker
passenger
policeman
pursuer
reporter
scrutiny
spy
traveller
vigil
visitor
wanderer
watchfulness
watchman