Taking place after alien crafts land around the world, an expert linguist is recruited by the military to determine whether they come in peace or are a threat.
| Louise Banks | Amy Adams |
| Ian Donnelly | Jeremy Renner |
| Colonel Weber | Forest Whitaker |
| Agent Halpern | Michael Stuhlbarg |
| Captain Marks | Mark O'Brien |
| General Shang | Tzi Ma |
| 8-Year-Old Hannah | Abigail Pniowsky |
| 12-Year-Old Hannah | Julia Scarlett Dan |
| 6-Year-Old Hannah | Jadyn Malone |
| Dr. Kettler | Frank Schorpion |
| Private Lasky | Lucas Chartier-Dessert |
| Private Combs | Christian Jadah |
| CNAC Anchor | Lucy Van Oldenbarneveld |
| Environmental Tech | Andrew Shaver |
| Environmental Tech | Pat Kiely |
| Dr. J. Bydwell | Sonia Vigneault |
| Richard Riley | Mark Camacho |
| Press Secretary | Sabrina Reeves |
| Australian Scientist | Julian Casey |
| British Scientist | Tony Robinow |
| CIA Officer Dan Ryder | Larry Day |
| Preacher | Matthew Willson |
| Chinese Scientist | Ruth Chiang |
| Chinese Scientist | Russell Yuen |
| Russian Officer | Sergiy Marchenko |
| Swedish Scientist | Anana Rydvald |
| Sudan Representative | Bineyam Girma |
| African Representative | Abdelghafour Elaaziz |
| Sierra Leone Representative | Abdul Ayoola |
| Japanese Minister | Alex M. Yeuh |
| Venezuelan Representative | Daniel Esteban |
| Chinese Man | Albert Kwan |
| Student with Smartphone | Brittany Teo |
| Cryptographer | Joe Cobden |
| Cryptographer | Lorne Brass |
| Cryptographer | Genevieve Sirois |
| Science Team Member | Victor Andres Trelles Turgeon |
| Science Team Member | Michael Nangreaves |
| Communications Operator | Reda Guerinik |
| Communications Operator | Adrien Benn |
| Communications Operator | Sasha Samar |
| Communications Operator | Kathleen Stavert |
| Nurse | Kattia Thony |
| Nurse | Leisa Reid |
| Lieutenant | Brent Skagford |
| Soldier | Gurdeep Ahluwalia |
| TV Anchor | Shawn Campbell |
| TV Anchor | Brian Dunstan |
| TV Anchor | Dan Duran |
| TV Anchor | Lori Graham |
| TV Anchor | Orla Johannes |
| TV Anchor | John Sanford Moore |
| TV Anchor | Sangita Patel |
| TV Anchor | Hal Roberts |
| TV Anchor | Camille Ross |
| TV Anchor | Ola Sturik |
| TV Anchor | Tammie Sutherland |
| TV Anchor | Max Walker |
| Motion Capture Heptapod | Marc-André Goulet |
| Motion Capture Heptapod | Paul-Antoine Taillefer |
| Motion Capture Heptapod | Martin Jr Pelletier |
| 4-Year-Old Hannah (uncredited) | Carmela Nozza Guizzo |
| Master Sergeant Douglas (uncredited) | Robert D. Morais |
| Foreign Correspondent (uncredited) | Mustafa Haidari |
| Halpern's Deputy Director (uncredited) | Philippe Hartmann |
| US Army Major (uncredited) | Laurean Adrian Parau |
| Gala Guest (uncredited) | Nathaly Thibault |
| Middle Aged Woman (uncredited) | Leslie Baker |
| Soldier (uncredited) | Dave Campbell |
| Venezuelan Military (uncredited) | Alexander Da Mota |
| Pakistani Scientist (uncredited) | Akul Dang |
| Soldier (uncredited) | Frank Fiola |
