An observer is someone who watches or notices something, often with the intention of gaining knowledge or understanding. A COMMENTATOR is someone who provides an opinion or analysis on a particular subject. A SIGHTSEER is someone who visits places of interest for pleasure. A BYSTANDER is someone who is present at an event but does not take part in it. A heeder is someone who pays attention to and obeys instructions. A SPY is someone who secretly collects information about an individual or organization. A BEHOLDER is someone who looks at or observes something. A VIEWER is someone who looks at or watches something. A noter is someone who takes notes or makes observations. An ONLOOKER is someone who watches something without taking part. A WATCHER is someone who keeps watch or guard. A LOOKER is someone who looks at something. A SPECTATOR is someone who watches a performance or event. A WITNESS is someone who sees or knows about an event. A SEER is someone who has prophetic vision or insight. An EYER is someone who looks at something. An EYEWITNESS is someone who has seen an event and can give a firsthand account of it.