Ethel Cox aka Gwendoline Cook (born 1888 – died about 1981) was a British suffragette.

In 1913, along with Mary Ann Aldham, she was found breaking windows at the house of the Home Secretary.

On 11 October 1913, she attempted to throw leaflets promoting women's suffrage into a Royal carriage.

In 2021 a hunger medal was shown on Antiques Roadshow on BBC2 as belonging to someone's grandmother who was named "Gwendoline Cook".

He had letters written by her to other leading suffragettes where she complained that she had failed to get arrested on another occasion.