Commentator
Part of speech: noun
Definition: a person who comments; especially someone who is paid to give one's opinions in the media about current affairs, sports, etc.
Example sentence: How could I not be the underdog, starting at 35 and a half and going from a manager and a fourth-string color commentator to being a wrestler?
Observer
Part of speech: noun
Definition: One who makes observations, monitors or takes noticeOne who adheres or follows laws, guidelines, etc.A person sent as a representative, to a meeting or other function to monitor but not to participateA crew member on an aircraft who makes observations of enemy positions or aircraftA sentry etc. manning an observation post
Example sentence: Who am I, really? I prefer to leave that up to the observer, because I will never finish answering that.