Louise
Louise is a linguist professor who is recruited by Colonel Banks to come to the heptapod site in Montana in an attempt to learn their language. She is the first to make contact with them and begins to study their language. Because of her boldness in being willing to do whatever it takes to speak to them, she discovers that the heptapods are there to give humanity a weapon: their language, which allows anyone who knows it to perceive the future, a blessing and a curse that Louise is the first to gain.
Ian
Ian is a physicist who has been recruited to find out why the heptapods have come to earth. We learn that he and Louise become married and have a child together after the heptapods leave earth. Louise has been given foresight by the heptapod language which carries with it a great price that she shares with Ian; it ultimately ends their marriage.
Colonel Weber
Colonel Weber is head of the military forces that have been stationed in Montana to observe and attempt to secure the heptapod's ship. He meets with Louise and chooses her for the job of translating the heptapod language in an attempt, which he believes will not work, to find peace between the two species without war.
Agent Halpern
Halpern is part of the task force which is on the ground at the arrival site of the heptapods in Montana. He has a direct line to the President of the United States and is seeking to do everything he can to ensure the safety of America. He follows orders and takes his initiative from the President, not Louise.
General Shang
General Shang is the head of China's defense forces. He believes that the heptapods have come to earth to start a war, and is convincing other countries to militarize in order to fight back as he believes humanity will be wiped out if they don't. He is the key to stopping the war which Louise learns towards the end of the plot.
