Clitheroe Royal Grammar School is a co-educational grammar school in the town of Clitheroe in Lancashire, England, formerly an all-boys school. It was founded in 1554 as "The Free Grammar School of King Philip and Queen Mary" "for the education, instruction and learning of boys and young men in grammar; to be and to continue for ever."

Clitheroe is a town and civil parish in the Borough of Ribble Valley, Lancashire, England; it is located 34 miles (55 km) north-west of Manchester. It is near the Forest of Bowland and is often used as a base for tourists visiting the area. In 2018, the Clitheroe built-up area had an estimated population of 16,279.