noticer

nouns

someone who takes notice
"a careful noticer of details"
noticer
is derived from
notice
is a type of (narrower)
a person who becomes aware (of things or events) through the senses
beholder, observer, perceiver, percipient
someone who gives formal notice
noticer
is a type of (narrower)
a worker who holds or is invested with an office
functionary, official