| John Hay Cossar | |
| Birth Date: | 2 January 1858 |
| Birth Place: | London, England, UK |
| Death Place: | Hollywood, California, US |
| Occupation: | Actor |
| Yearsactive: | 1914–29 |
John Hay Cossar (2 January 1858 - 28 April 1935) was an English actor of the silent era. He appeared in more than 140 films between 1914 and 1929.
Cossar was born in London, England. He was the fifth child of Walter Cossar and his wife Kate Lyster. Walter was in the Royal Marines between 1835 and 1863. In 1865 the family travelled to Canada and thence to Chicago, Illinois in the USA where John's older brother Walter Lyster Cossar later became City Editor of the Chicago Evening Journal.
In 1896, John married Fanny Cohen in Chicago. Fanny was also an actress and the 1930 census of Los Angeles shows them living with two children, Phyllis and Raymond. He died in Hollywood, California, in 1935.