Colossal

Anne Hathaway

Gloria

Jason Sudeikis

Oscar

Austin Stowell

Joel

Tim Blake Nelson

Garth

Dan Stevens

Tim

Hannah Cheramy

Young Gloria

Nathan Ellison

Young Oscar

Sarah Surh

Mother

Haeun Hannah Cho

Little Girl

Joe Costa

Old Man

Melissa M. Montgomery

Waitress

Christine Lee

Seoul Waitress

Rukiya Bernard

Maggie

James Yi

Fund Raiser Man

Alyssa Dawson

Reporter

Miho Suzuki

International News Anchor

Charles Singh

Expert #1

Jenny Mitchell

Expert #2

Mad Harper

Reporter #2

Everett Adams

Chubby Boy

Agam Darshi

Ash

Hettie Lynne Hurtes

News Reporting Consultant

Alex Cohen

News Reporting Consultant

Steve Julian

News Reporting Consultant

Andrew Suttar

Bar Patron (uncredited)

Cole Turner

Boy Walking By Playground (uncredited)