The Collaborative International Dictionary of English v.0.48:
Perceiver \Per*ceiv"er\ (p[~e]r*s[=e]v"[~e]r), n. One who perceives (in any of the senses of the verb). --Milton. [1913 Webster]WordNet (r) 3.0 (2006):
perceiver n 1: a person who becomes aware (of things or events) through the senses [syn: perceiver, percipient, observer, beholder]