Commentator (noun)
A person who comments; especially someone who is paid to give his/her opinions in the media about current affairs, sports, etc.
Commenter (noun)
One who comments.
Wiktionary
Commentator (noun)
a person who comments on events or on a text
“commentators noted that the demonstration was part of a wider strategy”
Commentator (noun)
a person who commentates on a sports match or other event
“the move electrified spectators and commentators alike”
Commenter (noun)
a person who expresses an opinion or engages in discussion of an issue or event, especially online in response to an article or blog post
“a regular commenter on many blogs”
“the first commenter suggested that the story is a hoax”
Oxford Dictionary