Amy Adams as Louise Banks

Jeremy Renner as Ian Donnelly

Forest Whitaker as Colonel Weber

Michael Stuhlbarg as Agent Halpern

Mark O'Brien as Captain Marks

Tzi Ma as General Shang

Abigail Pniowsky as 8-Year-Old Hannah

Julia Scarlett Dan as 12-Year-Old Hannah

Jadyn Malone as 6-Year-Old Hannah

Frank Schorpion as Dr. Kettler

Lucas Chartier-Dessert as Private Lasky

Christian Jadah as Private Combs

Lucy Van Oldenbarneveld as CNAC Anchor

Andrew Shaver as Environmental Tech

Pat Kiely as Environmental Tech

Sonia Vigneault as Dr. J. Bydwell

Mark Camacho as Richard Riley

Sabrina Reeves as Press Secretary

Julian Casey as Australian Scientist

Tony Robinow as British Scientist

Larry Day as CIA Officer Dan Ryder

Matthew Willson as Preacher

Ruth Chiang as Chinese Scientist

Russell Yuen as Chinese Scientist

Sergiy Marchenko as Russian Officer

Anana Rydvald as Swedish Scientist

Bineyam Girma as Sudan Representative

Abdelghafour Elaaziz as African Representative

Abdul Ayoola as Sierra Leone Representative

Alex M. Yeuh as Japanese Minister

Daniel Esteban as Venezuelan Representative

Albert Kwan as Chinese Man

Brittany Teo as Student with Smartphone

Joe Cobden as Cryptographer

Lorne Brass as Cryptographer

Genevieve Sirois as Cryptographer

Victor Andres Trelles Turgeon as Science Team Member

Michael Nangreaves as Science Team Member

Reda Guerinik as Communications Operator

Adrien Benn as Communications Operator

Sasha Samar as Communications Operator

Kathleen Stavert as Communications Operator

Kattia Thony as Nurse

Leisa Reid as Nurse

Brent Skagford as Lieutenant

Gurdeep Ahluwalia as Soldier

Shawn Campbell as TV Anchor

Brian Dunstan as TV Anchor

Dan Duran as TV Anchor

Lori Graham as TV Anchor

Orla Johannes as TV Anchor

John Sanford Moore as TV Anchor

Sangita Patel as TV Anchor

Hal Roberts as TV Anchor

Camille Ross as TV Anchor

Ola Sturik as TV Anchor

Tammie Sutherland as TV Anchor

Max Walker as TV Anchor

Marc-André Goulet as Motion Capture Heptapod

Paul-Antoine Taillefer as Motion Capture Heptapod

Martin Jr Pelletier as Motion Capture Heptapod

Carmela Nozza Guizzo as 4-Year-Old Hannah (uncredited)

Robert D. Morais as Master Sergeant Douglas (uncredited)

Mustafa Haidari as Foreign Correspondent (uncredited)

Philippe Hartmann as Halpern's Deputy Director (uncredited)

Laurean Adrian Parau as US Army Major (uncredited)

Nathaly Thibault as Gala Guest (uncredited)

Leslie Baker as Middle Aged Woman (uncredited)

Dave Campbell as Soldier (uncredited)

Alexander Da Mota as Venezuelan Military (uncredited)

Akul Dang as Pakistani Scientist (uncredited)

Frank Fiola as Soldier (uncredited)