WordNet: beholder, observer, perceiver, percipient

a person who becomes aware (of things or events) through the senses

• hypernym individual, mortal, person, somebody, someone, soul

• hyponym eyeglass wearer

• hyponym discoverer, finder, spotter

• hyponym attender, auditor, hearer, listener

• hyponym audile

• hyponym motile

• hyponym noticer

• hyponym seer

• hyponym looker, spectator, viewer, watcher, witness

• hyponym visualiser, visualizer

• hyponym informant, witness, witnesser

beholder

• (englanti) behold (derivationally related)
• (suomi) katselija (synonyymi)

observer

• (englanti) observe (derivationally related)

• (englanti) observe (derivationally related)

• (englanti) observe (derivationally related)
• (suomi) havainnoija (synonyymi)

• (suomi) havainnoitsija (synonyymi)

perceiver

• (englanti) perceive (derivationally related)
• (suomi) havaitsija (synonyymi)

percipient

• (suomi) näkijä (synonyymi)