katsoja (englanniksi)

viewer (s: jotakin katsova henkilö / tv:n / someone who watches television or computer screen)
spectator (s: jotakin katsova henkilö / urheilun / someone who views a spectacle / one who watches an event; especially, one held outdoors)
watcher (s: jotakin katsova henkilö)
looker (s: someone who watches or observes)
onlooker (s)
looker-on (s)
bystander (s: one who looks on or watches, without becoming involved or participating)
beholder (s: one who observes or beholds)